APA

Leavell U. W., Friebele M. L. & Cushman T. (1964). Widening horizons. Estados Unidos: American Book.

Chicago

Leavell Ullin W, Friebele Mary Louise and Cushman Tracie. 1964. Widening horizons. Estados Unidos: American Book.

Harvard

Leavell U. W., Friebele M. L. and Cushman T. (1964). Widening horizons. Estados Unidos: American Book.

MLA

Leavell Ullin W, Friebele Mary Louise and Cushman Tracie. Widening horizons. Estados Unidos: American Book. 1964.