English: 1-Photo: shopkeeper expresses a nation's gratitude for Dr. Salk's discovery.
Date
Source
March of Dimes Birth Defects Foundation; in book: Smith, Jane S. (1990). Patenting the Sun: Polio and The Salk Vaccine. New York: William Morrow. ISBN0688094945.
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.
{{Information |Description=Photo: shopkeeper expresses a nation's gratitude for Dr. Salk's discovery. |Source= March of Dimes Birth Defects Foundation |Date=April, 13, 1955 |Author=March of Dimes Birth Defects Foundation |Permission= |other_versions= }}