APA (7th ed.) Citation

Eberhart, M. G. (1956). The unknown quantity. Collins for the Crime Club.

Chicago Style (17th ed.) Citation

Eberhart, Mignon G. The Unknown Quantity. London: Collins for the Crime Club, 1956.

MLA (8th ed.) Citation

Eberhart, Mignon G. The Unknown Quantity. Collins for the Crime Club, 1956.

Warning: These citations may not always be 100% accurate.