APA (7th ed.) Citation

Sagan, H. (1992). Introduction to the calculus of variations. Dover Publications, Inc.

Chicago Style (17th ed.) Citation

Sagan, Hans. Introduction to the Calculus of Variations. New York: Dover Publications, Inc, 1992.

MLA (8th ed.) Citation

Sagan, Hans. Introduction to the Calculus of Variations. Dover Publications, Inc, 1992.

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