APA (7th ed.) Citation

Sagan, H. (1969). Introduction to the calculus of variations. McGraw-Hill Book Co., Inc.

Chicago Style (17th ed.) Citation

Sagan, Hans. Introduction to the Calculus of Variations. New York: McGraw-Hill Book Co., Inc, 1969.

MLA (9th ed.) Citation

Sagan, Hans. Introduction to the Calculus of Variations. McGraw-Hill Book Co., Inc, 1969.