Cita APA (7th ed.)

Struve, O., & Zebergs, V. (1962). Astronomy of the 20th century. Macmillan.

Cita Chicago (17th ed.)

Struve, Otto, i Velta Zebergs. Astronomy of the 20th Century. New York: Macmillan, 1962.

Cita MLA (9th ed.)

Struve, Otto, i Velta Zebergs. Astronomy of the 20th Century. Macmillan, 1962.