APA (7th ed.) Citation

Asimov, I. (1973). The Foundation trilogy. Panther Books.

Chicago Style (17th ed.) Citation

Asimov, Isaac. The Foundation Trilogy. Frogmore: Panther Books, 1973.

MLA (8th ed.) Citation

Asimov, Isaac. The Foundation Trilogy. Panther Books, 1973.

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