APA (7th ed.) Citation

Ballou, D. H., & Steen, F. H. (1943). Plane and spherical trigonometry. Ginn.

Chicago Style (17th ed.) Citation

Ballou, Donald Henry, and Frederick Henry Steen. Plane and Spherical Trigonometry. Boston: Ginn, 1943.

MLA (9th ed.) Citation

Ballou, Donald Henry, and Frederick Henry Steen. Plane and Spherical Trigonometry. Ginn, 1943.