A source book in astronomy

MLA

Shapley, Harlow, and Helen Ethel Howarth. A Source Book In Astronomy. 1st ed., 2nd impres. New York: McGraw-Hill, 1929.

APA

Shapley, H., & Howarth, H. Ethel. (1929). A source book in astronomy. 1st ed., 2nd impres. New York: McGraw-Hill.

Chicago

Shapley, Harlow, and Helen Ethel Howarth. A Source Book In Astronomy. 1st ed., 2nd impres. New York: McGraw-Hill, 1929.