Inscription: Photographer's stamp in ink on print, verso C: "COPYRIGHT // THE FOLLOWING CREDIT LINE MUST BE USED // [copyright symbol] KARSH, OTTAWA"; inscribed in pencil on print, verso UC: "Dr. Jonas Salk"; inscribed in pencil on print, verso LL: "C.N."
Yousuf Karsh, via Jo Tartt
Karsh, Yousuf. Portraits of Greatness. New York: Thomas Nelson and Sons, Ltd., 1959. p. 173.