APA (7th ed.) Citation

Shapley, H., & Howarth, H. E. (1929). A source book in astronomy. McGraw-Hill.

Chicago Style (17th ed.) Citation

Shapley, Harlow, and Helen E. Howarth. A Source Book in Astronomy. New York: McGraw-Hill, 1929.

MLA (9th ed.) Citation

Shapley, Harlow, and Helen E. Howarth. A Source Book in Astronomy. McGraw-Hill, 1929.