Cita APA (7th ed.)

Drooyan, I. (1977). Essentials of trigonometry (2nd ed.). Macmillan Publishing.

Cita Chicago (17th ed.)

Drooyan, Irving. Essentials of Trigonometry. 2nd ed. New York: Macmillan Publishing, 1977.

Cita MLA (9th ed.)

Drooyan, Irving. Essentials of Trigonometry. 2nd ed. Macmillan Publishing, 1977.