Adirondack Collection/Saranac Free Library: [>] (both), [>], [>], [>], [>], [>]
Authors’ collection: [>], [>], [>]
Bettmann/Corbis: [>]
British Museum: [>]
Byron Co./Museum of the City of New York: [>]
Centers for Disease Control: [>]
Corbis Images: [>], [>], [>], [>], [>]
Dennis Balibouse/Reuters/Corbis: [>]
Dennis Kunkel Microscopy, Inc./ Visuals Unlimited/Corbis: [>] (right)
Diane Deaton-Street: [>]
General Photographic Agency/Getty Images: [>] (top)
Historical Collections, College of Physicians of Philadelphia: [>]
Hulton-Deutsch Collection/Corbis: [>]
Indiana State Library: [>], [>]
Jacob Riis Collection/Museum of the City of New York: [>], [>]
John P. McGovern Historical Collections and Research Center, Houston Academy of Medicine/ Texas Medical Center Library: [>]
Library of Congress: x, [>], [>] (top), [>], [>], [>], [>], [>], [>], [>]
Los Angeles Public Library: [>], [>]
Marsha Miller, University of Texas at Austin: [>] (left)
Merck Archives: [>]
Modern Art Foundation in Situ, Poland: [>]
National Library of Medicine: [>], [>], [>], [>], [>], [>], [>], [>], [>], [>], [>], [>] (both), [>], [>], [>], [>]
National Portrait Gallery, London: [>]
Natural History Museum, London: [>]
Ohio Historical Society: [>]
Public Health Image Library/ Centers for Disease Control: [>] (bottom)
The Royal Society: [>]
Science Museum/SSPL/London: [>]
Security Pacific Collection/Los Angeles Public Library: [>]
Spencer Platt/Getty Images: [>]
Statens Museum for Kunst, Copenhagen: [>]
Tate Gallery, London: [>] Trudeau Institute Archives: [>]
University of Illinois at Urbana-Champaign: [>]
Visiting Nurse Service of New York: [>]
Wellcome Library, London: [>], [>]
Wellcome Trust, London: [>]
World Lung Association: [>]