Cita APA

Walker, J. n. 1., & Olk, J. (1970). Problems of conservation, our natural resources. Chicago, III.: Encyclopaedia Britannica Educational Corp.

Citación estilo Chicago

Walker, John n. 1906, y Jerry Olk. Problems of Conservation, Our Natural Resources. Chicago, III.: Encyclopaedia Britannica Educational Corp, 1970.

Cita MLA

Walker, John n. 1906, y Jerry Olk. Problems of Conservation, Our Natural Resources. Chicago, III.: Encyclopaedia Britannica Educational Corp, 1970.