CLINICAL REVIEW
David W. Eisele, MD, Section Editor
Clar as Mud? Origins of the head mirror: A historical note Ollivier Laccourreye, MD,1* Alfred Werner, MD,1 Iain McGill, MD,2 F. Christopher Holsinger, MD3 1
Department of Otorhinolaryngology – Head and Neck Surgery, Universite Paris Descartes Sorbonne Paris Cite, H^opital Europeen Georges Pompidou, Paris, France, 2Place du Pl^atre, Saint Laurent de Chamousset, France, 3Division of Head and Neck Surgery, Department of Otolaryngology, Stanford University, Palo Alto, California.
Accepted 17 April 2015 Published online 14 July 2015 in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/hed.24093
ABSTRACT: In Europe, the name “Clar” immediately evokes to any otorhinolaryngologist the classic head mirror that remains a symbol of our profession. Yet, the origin of Clar has never been investigated. In this clinical and historical review, based on an Internet and PubMed database search together with perusal of Fischer’s Biographical Lexikon, the authors seek to elucidate this medical enigma. The data presented suggest that Clar was not a physician
but rather a term picked by the company that designed the mirror by the end of the 19th century to underscore the bright and sharp C 2015 Wiley view provided by this then innovative medical device. V Periodicals, Inc. Head Neck 38: 930–932, 2016
INTRODUCTION
would not be set up until 1913, in the city of Bordeaux.3–5 In his book, devoted to the treatment of diseases of the nasal cavities, facial sinuses and rhinopharynx, Marcel Lermoyez2 analyzed the various techniques then available to physicians for examining the ears, nasal cavities, oral cavity, pharynx, and larynx. He explained how direct lighting is not the best idea as, despite all refinements, it can never avoid there being an angle between the light-source and the observer’s eye, leaving anfractuous areas in shadow (Figure 2A).2 His preference was for reflected lighting, which he refers to as the “foreign method” because to him “. . .although reflected lighting of the ears and larynx has been used from the outset in Austria, Germany, and Britain, in France, where the penetration of any progress comes up against systematic opposition from the start, it has taken longer to replace the bad method of direct lighting. . ..”2 He observed that indirect lighting was a technique borrowed from the oculists, who sought a device to illuminate the eye’s fundus such that the observer’s pupil would, in effect, be the source of the light, “visual ray,” and “light ray” coinciding on the region of interest.2 Although Archibald Cleland,6 a Scottish military surgeon, had devised a direct lighting system around 1741 using a concave mirror with a candle, it was in 1851 that a German physician, Helmholtz,7 resolved the problem by reflecting the light via a glass plate held obliquely in front of the observer’s eye, thereby inventing the ophthalmoscope. Lermoyez2 reported how Coccius replaced Helmholtz’s glass plate by a flat mirror with a hole in the middle, Ruete replaced the flat mirror by a concave one, and Czermak introduced this device in laryngology after it had been applied in otology by von Tr€oltsch. Lermoyez2 devoted several pages of his book to the concave mirror, stressing the importance of the concavity
In Europe, the name “Clar” immediately evokes in the mind of the otorhinolaryngologist-head and neck surgeon the classic head mirror, which remains a symbol of our profession (Figure 1). Yet, when one enters the search terms “Clar” and “mirror” in the PubMed database, just 1 article mentioning a physician, Dr. Clar, dating from 1955, comes up.1 A Google search, in contrast, generates no less than 10,700,000 hits—but with nothing at all about Clar himself (or herself?). The person behind the mirror would seem to have left no written trace, despite such an overwhelming presence. Who, then, was this Clar of the eponymous head-mirror? Such is the question this clinical and historical review seeks to elucidate.
Clar’s mirror Clar’s mirror was first mentioned in the French medical literature in 1896, in a book written by Marcel Lermoyez.2 At this period in France, otorhinolaryngology (ORL) was just beginning to emerge as a field. The first edition of the Annales des Maladies de l’Oreille et du Larynx, forerunner of the present journal of the French Society of Otorhinolaryngology, came out in 1875, when the Society was in its third year of existence. At the time, there were no university departments of ORL and the first
*Corresponding author: O. Laccourreye, Department of Otorhinolaryngology – Head and Neck Surgery, H^opital Europeen Georges Pompidou, 20–40, Rue Leblanc, 75015, Paris, France. E-mail: [email protected] Contract grant sponsor: This study was supported in part by the Fulbright U.S. Scholars Grant Program, Washington, DC, and the Progre`s 2000 Association. Paris, France.
930
HEAD & NECK—DOI 10.1002/HED
JUNE 2016
KEY WORDS: mirror, otorhinolaryngology, history
ORIGINS
FIGURE 1. Clar mirror as depicted in 1896 by M. Lermoyez.2
determining focal length, the diameter determining the amount of light reflected, the frontal positioning at the root of the nose freeing both the observer’s hands, the binocular vision so as not to lose depth perception, and of being able to use the same mirror to examine both the ears and the larynx.2 At the end of the chapter, Lermoyez2 included a paragraph on electrical reflected lighting and the apparatus he called “Clar’s mirror” (miroir de Clar). He wrote that it was manufactured by the Reiner Company in Vienna, and comprised a spherically concave mirror of 10-cm diameter, pierced by 2 holes, combined with a small 6- to 10-volt incandescent light (Figure 1). He gave several reasons why he considered that “. . . this mirror is the best lighting device yet to be used. . ..” The quality of the incandescent light was identical to sunlight. Focal length could be set at will by the hinge that adjusted the position of the incandescent bulb in front of the mirror, enabling both otological and laryngological examination. The observer’s vision was binocular, thanks to 2 holes pierced at eye level. The frontal support left both the observer’s hands free. Finally, Lermoyez2 considered that “. . .its diameter gives it the advantage of shielding the face from the patient’s spittle. . ..”
OF THE HEAD MIRROR
In none of these publications, however, are there any references that let us know just who this doctor is or understand how and why his name comes to be given to the mirror. What, then, is this Reiner Company that lies at the origin of the most widely used light source for European otorhinolaryngologists until the advent of cold light generators and optic fiber? The founder was Carl B. Reiner. After completing his craft apprenticeship in the family surgical instrument firm in Vienna, in 1857, he left for Belgium to learn the art of high-quality mirror making by silver galvanization on glass.10 On his return, he started up the first factory in Vienna to specialize in mirrors; in 1912, his son, Karl, oversaw the merger with his grandfather’s firm.10 Barany, Pollitzer, and Chiari were just 3 of Reiner’s customers.10 A search of the Internet and PubMed database and perusal of Fischer’s Biographical Lexikon,11 as well as data sent by the Reiner Company after our inquiries, retrieved 2 physicians named Clar who could be related to the famous mirror described above. The first physician is Joseph Clar Beck, who was born on June 25, 1870, in Bohemia and, before dying in America in 1942, specialized in ophthalmology and otolaryngology, worked with the Red Cross in France during the First World War, and became Associated Dean of the Illinois Charitable Eye and Ear Infirmary.12 His autobiography made it clear that, in 1896, he was working in Chicago with his brother Carl (a doctor himself), having emigrated to the United States in 1884 and completed his medical studies at the College of Physicians and Surgeons (the future University of Illinois) in 1894.12 It was not only 1898 when Joseph Clar Beck came back to Europe, he then spent 3 years in Prague to extend his training in the Pathologisches Institut under Chiari’s guidance, where he studied otolaryngology
Clar the man? In 1882, Morell Mackenzie,8 in a treatise devoted to Diseases of the Larynx, Pharynx, and Trachea, spent 60 pages detailing the instrumentation required by good laryngological practice. In the chapter on mirrors, he made no mention of Clar’s mirror, and the name Clar did not feature in its “Alphabetic Table of Subjects and Authors.”8 In 1896, Marcel Lermoyez2 noted that the medical equipment manufacturer, Reiner, marketed a frontal lighting system, the name of which he translated as “Clar’s mirror” (. . . miroir de Clar . . .). In addition, in 1901, Dr. Victor Urbantschitsch,9 in Vienna, published a Manual of Otology in which he relates that, to improve the examination of his patients, he prefers the “. . .recent mirror of Dr. Clar of Vienna, manufactured by Reiner.”
FIGURE 2. (A) View of an anfractuous cavity achieved using direct lighting, as drawn by Lermoyez in 18962 (dark areas are not visualized because of lack of light). (B) Improvement in vision of an anfractuous cavity achieved using reflected lighting, when compared to (A).
HEAD & NECK—DOI 10.1002/HED
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LACCOURREYE ET AL.
and ophthalmology.12 The second one is Konrad Clemens Clar (or also Klar) born in Vienna in 1844 and son of Franz Clar professor of general pathology, therapy, and pharmacology.13 In 1869, in Graz, 5 years after graduating in philosophy, Konrad Clar became a doctor of medicine.13 According to his biography, Konrad Clar was qualified in balneotherapy in Graz in 1870, then transferred in 1888 to the University of Vienna where he lectured on balneology and climatotherapy before being invested as extraordinary university professor with “. . . the duty to hold of a two-hour council in each winter semester. . ..”13 He also had a major interest in geology and died in Vienna in 1904.13
Clar as mud? To us, it is clear than neither of these 2 physicians can be considered as the Clar of the mirror. None of them ever mentioned this mirror in a publication. Furthermore, “Joseph” was starting to practice medicine and had not yet specialized as an otolaryngologist when the first mention of the mirror was made in the literature in 1896. Similarly, “Konrad” never specialized in otolaryngology, and his main fields of interest (balneotherapy, climatotherapy, and geology) makes it hard to conceive how he could have been interested in the development of a frontal head mirror. Therefore, if one takes into account that the world Clar was not picked to design a physician but something else, 2 possible nonmedical, more literary explanations for the name borne by this mirror manufactured in the late 19th century, should be considered. Because the word “Klar” in German means “clear,” the close term Clar could have been used to refer to the bright, sharp view that the mirror provides. The second suggestion is that Clar is an anagram of the given name of the craftsman who first produced the mirror: Carl B. Reiner. Therefore, the “Clar mirror” that the Reiner Company presented in its catalog for over a century could
932
HEAD & NECK—DOI 10.1002/HED
JUNE 2016
seem to be Carl’s “clear mirror,” and the good Dr. Clar to be a looking-glass character, a virtual image, a ghost! Regardless, the absence of a historical regard makes it clear that the origins of this important innovation in ORL may remain as “Clar” as mud.
CONCLUSION This inquiry cleared up a point of otorhinolaryngological history that has remained somewhat shadowy but also demonstrated the importance (stressed by all “modern” medical journal editors) to provide references for all proper names cited, the care and rigor with which all authors should draw up their reference lists, and the need to think twice before rushing into the translation of technical terms.
REFERENCES 1. Lepp FH. Lighting problems in dental, stomatological and maxillary therapeutics: Clar electrical headlamp with mirror [in German]. Zahnarztl Welt 1955;10:420–421. 2. Lermoyez M. Therapeutique des maladies des fosses nasales, des sinus de la face et du pharynx nasal. Paris: Octave Doin; 1896. pp 27–45. 3. Laccourreye O, Chabolle F, Fraysse B, Chevalier D, Martin C. At the crossroads. Eur Ann Otorhinolaryngol Head Neck Dis 2015;132:1–2. 4. Laccourreye O, McGill I, Werner W, Martin C. Who am I? Eur Ann Otorhinolaryngol Head Neck Dis 2014. [Epub ahead of print]. 5. Legent F. La naissance de l’otorhinolaryngologie en France. Available at: http://ww.biusante.parisdescartes.fr/histmed/medica/orlc.htm. Accessed March 1, 2015. 6. Segal A. Histoire des sciences medicales. Colombes: Les editions de Medecine Pratique; 1979. pp 395–406. 7. von Helmholtz HLF. Beschreibung eines Augen-Spiegels. Berlin; A F€ orstner’sche Verlagsbuchhandlung; 1851. 8. Mackenzie M, Moure EJ, Bertier F. Traite Pratique des Maladies du Larynx du Pharynx et de la Trachee. Paris: Octave Doin; 1882. 9. Urbantschitsch V. Lehrbuch der Ohrenheilkunde. Berlin, Vienne: Urban und Schwarzenberg; 1901. p 1. 10. Carl Reiner GmbH. L’historique de l’entreprise. Available at: http://carlreiner.at/index.php/fr/unternehmen-19/historique. Accessed March 1, 2015. 11. Fischer I. Biographisches Lexikon der Hervorragen Arzte. Berlin, Vienna: Urban und Schwarzenberg; 1932. 12. Beck JC. Fifty years in medicine. Chicago: McDonough & Company; 1940. 13. Duffin CT, Moody RTJ, Gardner–Thorpe C. A history of geology and medicine. Oxford: Geological Society of London; 2013. p 452.
David W. Eisele, MD, Section Editor
Clar as Mud? Origins of the head mirror: A historical note Ollivier Laccourreye, MD,1* Alfred Werner, MD,1 Iain McGill, MD,2 F. Christopher Holsinger, MD3 1
Department of Otorhinolaryngology – Head and Neck Surgery, Universite Paris Descartes Sorbonne Paris Cite, H^opital Europeen Georges Pompidou, Paris, France, 2Place du Pl^atre, Saint Laurent de Chamousset, France, 3Division of Head and Neck Surgery, Department of Otolaryngology, Stanford University, Palo Alto, California.
Accepted 17 April 2015 Published online 14 July 2015 in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/hed.24093
ABSTRACT: In Europe, the name “Clar” immediately evokes to any otorhinolaryngologist the classic head mirror that remains a symbol of our profession. Yet, the origin of Clar has never been investigated. In this clinical and historical review, based on an Internet and PubMed database search together with perusal of Fischer’s Biographical Lexikon, the authors seek to elucidate this medical enigma. The data presented suggest that Clar was not a physician
but rather a term picked by the company that designed the mirror by the end of the 19th century to underscore the bright and sharp C 2015 Wiley view provided by this then innovative medical device. V Periodicals, Inc. Head Neck 38: 930–932, 2016
INTRODUCTION
would not be set up until 1913, in the city of Bordeaux.3–5 In his book, devoted to the treatment of diseases of the nasal cavities, facial sinuses and rhinopharynx, Marcel Lermoyez2 analyzed the various techniques then available to physicians for examining the ears, nasal cavities, oral cavity, pharynx, and larynx. He explained how direct lighting is not the best idea as, despite all refinements, it can never avoid there being an angle between the light-source and the observer’s eye, leaving anfractuous areas in shadow (Figure 2A).2 His preference was for reflected lighting, which he refers to as the “foreign method” because to him “. . .although reflected lighting of the ears and larynx has been used from the outset in Austria, Germany, and Britain, in France, where the penetration of any progress comes up against systematic opposition from the start, it has taken longer to replace the bad method of direct lighting. . ..”2 He observed that indirect lighting was a technique borrowed from the oculists, who sought a device to illuminate the eye’s fundus such that the observer’s pupil would, in effect, be the source of the light, “visual ray,” and “light ray” coinciding on the region of interest.2 Although Archibald Cleland,6 a Scottish military surgeon, had devised a direct lighting system around 1741 using a concave mirror with a candle, it was in 1851 that a German physician, Helmholtz,7 resolved the problem by reflecting the light via a glass plate held obliquely in front of the observer’s eye, thereby inventing the ophthalmoscope. Lermoyez2 reported how Coccius replaced Helmholtz’s glass plate by a flat mirror with a hole in the middle, Ruete replaced the flat mirror by a concave one, and Czermak introduced this device in laryngology after it had been applied in otology by von Tr€oltsch. Lermoyez2 devoted several pages of his book to the concave mirror, stressing the importance of the concavity
In Europe, the name “Clar” immediately evokes in the mind of the otorhinolaryngologist-head and neck surgeon the classic head mirror, which remains a symbol of our profession (Figure 1). Yet, when one enters the search terms “Clar” and “mirror” in the PubMed database, just 1 article mentioning a physician, Dr. Clar, dating from 1955, comes up.1 A Google search, in contrast, generates no less than 10,700,000 hits—but with nothing at all about Clar himself (or herself?). The person behind the mirror would seem to have left no written trace, despite such an overwhelming presence. Who, then, was this Clar of the eponymous head-mirror? Such is the question this clinical and historical review seeks to elucidate.
Clar’s mirror Clar’s mirror was first mentioned in the French medical literature in 1896, in a book written by Marcel Lermoyez.2 At this period in France, otorhinolaryngology (ORL) was just beginning to emerge as a field. The first edition of the Annales des Maladies de l’Oreille et du Larynx, forerunner of the present journal of the French Society of Otorhinolaryngology, came out in 1875, when the Society was in its third year of existence. At the time, there were no university departments of ORL and the first
*Corresponding author: O. Laccourreye, Department of Otorhinolaryngology – Head and Neck Surgery, H^opital Europeen Georges Pompidou, 20–40, Rue Leblanc, 75015, Paris, France. E-mail: [email protected] Contract grant sponsor: This study was supported in part by the Fulbright U.S. Scholars Grant Program, Washington, DC, and the Progre`s 2000 Association. Paris, France.
930
HEAD & NECK—DOI 10.1002/HED
JUNE 2016
KEY WORDS: mirror, otorhinolaryngology, history
ORIGINS
FIGURE 1. Clar mirror as depicted in 1896 by M. Lermoyez.2
determining focal length, the diameter determining the amount of light reflected, the frontal positioning at the root of the nose freeing both the observer’s hands, the binocular vision so as not to lose depth perception, and of being able to use the same mirror to examine both the ears and the larynx.2 At the end of the chapter, Lermoyez2 included a paragraph on electrical reflected lighting and the apparatus he called “Clar’s mirror” (miroir de Clar). He wrote that it was manufactured by the Reiner Company in Vienna, and comprised a spherically concave mirror of 10-cm diameter, pierced by 2 holes, combined with a small 6- to 10-volt incandescent light (Figure 1). He gave several reasons why he considered that “. . . this mirror is the best lighting device yet to be used. . ..” The quality of the incandescent light was identical to sunlight. Focal length could be set at will by the hinge that adjusted the position of the incandescent bulb in front of the mirror, enabling both otological and laryngological examination. The observer’s vision was binocular, thanks to 2 holes pierced at eye level. The frontal support left both the observer’s hands free. Finally, Lermoyez2 considered that “. . .its diameter gives it the advantage of shielding the face from the patient’s spittle. . ..”
OF THE HEAD MIRROR
In none of these publications, however, are there any references that let us know just who this doctor is or understand how and why his name comes to be given to the mirror. What, then, is this Reiner Company that lies at the origin of the most widely used light source for European otorhinolaryngologists until the advent of cold light generators and optic fiber? The founder was Carl B. Reiner. After completing his craft apprenticeship in the family surgical instrument firm in Vienna, in 1857, he left for Belgium to learn the art of high-quality mirror making by silver galvanization on glass.10 On his return, he started up the first factory in Vienna to specialize in mirrors; in 1912, his son, Karl, oversaw the merger with his grandfather’s firm.10 Barany, Pollitzer, and Chiari were just 3 of Reiner’s customers.10 A search of the Internet and PubMed database and perusal of Fischer’s Biographical Lexikon,11 as well as data sent by the Reiner Company after our inquiries, retrieved 2 physicians named Clar who could be related to the famous mirror described above. The first physician is Joseph Clar Beck, who was born on June 25, 1870, in Bohemia and, before dying in America in 1942, specialized in ophthalmology and otolaryngology, worked with the Red Cross in France during the First World War, and became Associated Dean of the Illinois Charitable Eye and Ear Infirmary.12 His autobiography made it clear that, in 1896, he was working in Chicago with his brother Carl (a doctor himself), having emigrated to the United States in 1884 and completed his medical studies at the College of Physicians and Surgeons (the future University of Illinois) in 1894.12 It was not only 1898 when Joseph Clar Beck came back to Europe, he then spent 3 years in Prague to extend his training in the Pathologisches Institut under Chiari’s guidance, where he studied otolaryngology
Clar the man? In 1882, Morell Mackenzie,8 in a treatise devoted to Diseases of the Larynx, Pharynx, and Trachea, spent 60 pages detailing the instrumentation required by good laryngological practice. In the chapter on mirrors, he made no mention of Clar’s mirror, and the name Clar did not feature in its “Alphabetic Table of Subjects and Authors.”8 In 1896, Marcel Lermoyez2 noted that the medical equipment manufacturer, Reiner, marketed a frontal lighting system, the name of which he translated as “Clar’s mirror” (. . . miroir de Clar . . .). In addition, in 1901, Dr. Victor Urbantschitsch,9 in Vienna, published a Manual of Otology in which he relates that, to improve the examination of his patients, he prefers the “. . .recent mirror of Dr. Clar of Vienna, manufactured by Reiner.”
FIGURE 2. (A) View of an anfractuous cavity achieved using direct lighting, as drawn by Lermoyez in 18962 (dark areas are not visualized because of lack of light). (B) Improvement in vision of an anfractuous cavity achieved using reflected lighting, when compared to (A).
HEAD & NECK—DOI 10.1002/HED
JUNE 2016
931
LACCOURREYE ET AL.
and ophthalmology.12 The second one is Konrad Clemens Clar (or also Klar) born in Vienna in 1844 and son of Franz Clar professor of general pathology, therapy, and pharmacology.13 In 1869, in Graz, 5 years after graduating in philosophy, Konrad Clar became a doctor of medicine.13 According to his biography, Konrad Clar was qualified in balneotherapy in Graz in 1870, then transferred in 1888 to the University of Vienna where he lectured on balneology and climatotherapy before being invested as extraordinary university professor with “. . . the duty to hold of a two-hour council in each winter semester. . ..”13 He also had a major interest in geology and died in Vienna in 1904.13
Clar as mud? To us, it is clear than neither of these 2 physicians can be considered as the Clar of the mirror. None of them ever mentioned this mirror in a publication. Furthermore, “Joseph” was starting to practice medicine and had not yet specialized as an otolaryngologist when the first mention of the mirror was made in the literature in 1896. Similarly, “Konrad” never specialized in otolaryngology, and his main fields of interest (balneotherapy, climatotherapy, and geology) makes it hard to conceive how he could have been interested in the development of a frontal head mirror. Therefore, if one takes into account that the world Clar was not picked to design a physician but something else, 2 possible nonmedical, more literary explanations for the name borne by this mirror manufactured in the late 19th century, should be considered. Because the word “Klar” in German means “clear,” the close term Clar could have been used to refer to the bright, sharp view that the mirror provides. The second suggestion is that Clar is an anagram of the given name of the craftsman who first produced the mirror: Carl B. Reiner. Therefore, the “Clar mirror” that the Reiner Company presented in its catalog for over a century could
932
HEAD & NECK—DOI 10.1002/HED
JUNE 2016
seem to be Carl’s “clear mirror,” and the good Dr. Clar to be a looking-glass character, a virtual image, a ghost! Regardless, the absence of a historical regard makes it clear that the origins of this important innovation in ORL may remain as “Clar” as mud.
CONCLUSION This inquiry cleared up a point of otorhinolaryngological history that has remained somewhat shadowy but also demonstrated the importance (stressed by all “modern” medical journal editors) to provide references for all proper names cited, the care and rigor with which all authors should draw up their reference lists, and the need to think twice before rushing into the translation of technical terms.
REFERENCES 1. Lepp FH. Lighting problems in dental, stomatological and maxillary therapeutics: Clar electrical headlamp with mirror [in German]. Zahnarztl Welt 1955;10:420–421. 2. Lermoyez M. Therapeutique des maladies des fosses nasales, des sinus de la face et du pharynx nasal. Paris: Octave Doin; 1896. pp 27–45. 3. Laccourreye O, Chabolle F, Fraysse B, Chevalier D, Martin C. At the crossroads. Eur Ann Otorhinolaryngol Head Neck Dis 2015;132:1–2. 4. Laccourreye O, McGill I, Werner W, Martin C. Who am I? Eur Ann Otorhinolaryngol Head Neck Dis 2014. [Epub ahead of print]. 5. Legent F. La naissance de l’otorhinolaryngologie en France. Available at: http://ww.biusante.parisdescartes.fr/histmed/medica/orlc.htm. Accessed March 1, 2015. 6. Segal A. Histoire des sciences medicales. Colombes: Les editions de Medecine Pratique; 1979. pp 395–406. 7. von Helmholtz HLF. Beschreibung eines Augen-Spiegels. Berlin; A F€ orstner’sche Verlagsbuchhandlung; 1851. 8. Mackenzie M, Moure EJ, Bertier F. Traite Pratique des Maladies du Larynx du Pharynx et de la Trachee. Paris: Octave Doin; 1882. 9. Urbantschitsch V. Lehrbuch der Ohrenheilkunde. Berlin, Vienne: Urban und Schwarzenberg; 1901. p 1. 10. Carl Reiner GmbH. L’historique de l’entreprise. Available at: http://carlreiner.at/index.php/fr/unternehmen-19/historique. Accessed March 1, 2015. 11. Fischer I. Biographisches Lexikon der Hervorragen Arzte. Berlin, Vienna: Urban und Schwarzenberg; 1932. 12. Beck JC. Fifty years in medicine. Chicago: McDonough & Company; 1940. 13. Duffin CT, Moody RTJ, Gardner–Thorpe C. A history of geology and medicine. Oxford: Geological Society of London; 2013. p 452.
