APA

Keiser N. F., . (1961). Introductory economics. New York: Wiley.

Chicago

Keiser Norman Fred, . 1961. Introductory economics. New York: Wiley.

Harvard

Keiser N. F., . (1961). Introductory economics. New York: Wiley.

MLA

Keiser Norman Fred, . Introductory economics. New York: Wiley. 1961.