APA

Littlewood D., . (1949). The skeleton key of mathematics. New York: Hutchinson's University Library.

Chicago

Littlewood D.E, . 1949. The skeleton key of mathematics. New York: Hutchinson's University Library.

Harvard

Littlewood D., . (1949). The skeleton key of mathematics. New York: Hutchinson's University Library.

MLA

Littlewood D.E, . The skeleton key of mathematics. New York: Hutchinson's University Library. 1949.