APA (7th ed.) Citation

Forsyth, A. R. (1927). Calculus of variations. The University Press.

Chicago Style (17th ed.) Citation

Forsyth, Andrew Russell. Calculus of Variations. Cambridge [England]: The University Press, 1927.

MLA (9th ed.) Citation

Forsyth, Andrew Russell. Calculus of Variations. The University Press, 1927.