Reader's Digest Association. (1996). Great mysteries of the 20th century. Reader's Digest.
Chicago-referens (17:e uppl.)Reader's Digest Association. Great Mysteries of the 20th Century. Pleasantville: Reader's Digest, 1996.
MLA-referens (9:e uppl.)Reader's Digest Association. Great Mysteries of the 20th Century. Reader's Digest, 1996.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.