Wagner, G. (1940). Letter in German to Paul Heuduck, February 12, 1940. Saint Louis University Libraries Digitization Center.
Chicago-referens (17:e uppl.)Wagner, Gerdt. Letter in German to Paul Heuduck, February 12, 1940. Saint Louis University Libraries Digitization Center, 1940.
MLA-referens (8:e uppl.)Wagner, Gerdt. Letter in German to Paul Heuduck, February 12, 1940. Saint Louis University Libraries Digitization Center, 1940.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.