APA (7th ed.) Citation

Lovecraft, H. P., & Derleth, A. W. (1970). The lurker at the threshold. Panther Books.

Chicago Style (17th ed.) Citation

Lovecraft, H. P., and August William Derleth. The Lurker at the Threshold. London: Panther Books, 1970.

MLA (9th ed.) Citation

Lovecraft, H. P., and August William Derleth. The Lurker at the Threshold. Panther Books, 1970.

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