APA (7th ed.) Citation

Heard, G. (1950). The riddle of the flying saucers: Is Another World Watching? By Gerald Heard ((1st publ.).). Carroll & Nicholson.

Chicago Style (17th ed.) Citation

Heard, Gerald. The Riddle of the Flying Saucers: Is Another World Watching? By Gerald Heard. (1st publ.). London: Carroll & Nicholson, 1950.

MLA (9th ed.) Citation

Heard, Gerald. The Riddle of the Flying Saucers: Is Another World Watching? By Gerald Heard. (1st publ.). Carroll & Nicholson, 1950.