APA (7th ed.) Citation

Reader's Digest Association. (1996). Great mysteries of the 20th century. Reader's Digest.

Chicago Style (17th ed.) Citation

Reader's Digest Association. Great Mysteries of the 20th Century. Pleasantville: Reader's Digest, 1996.

MLA (9th ed.) Citation

Reader's Digest Association. Great Mysteries of the 20th Century. Reader's Digest, 1996.