APA (7th ed.) Citation

Fox, C. (1987). An introduction to the calculus of variations / by Charles Fox. Dover Publications.

Chicago Style (17th ed.) Citation

Fox, Charles. An Introduction to the Calculus of Variations / by Charles Fox. New York: Dover Publications, 1987.

MLA (9th ed.) Citation

Fox, Charles. An Introduction to the Calculus of Variations / by Charles Fox. Dover Publications, 1987.

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