APA

Zweifel R. G., . (1955). Ecology, distribution, and systematics of frogs of the Rana boylei group. Berkeley, Calif. [u.a.]: Univ. of California Press.

Chicago

Zweifel Richard G, . 1955. Ecology, distribution, and systematics of frogs of the Rana boylei group. Berkeley, Calif. [u.a.]: Univ. of California Press.

Harvard

Zweifel R. G., . (1955). Ecology, distribution, and systematics of frogs of the Rana boylei group. Berkeley, Calif. [u.a.]: Univ. of California Press.

MLA

Zweifel Richard G, . Ecology, distribution, and systematics of frogs of the Rana boylei group. Berkeley, Calif. [u.a.]: Univ. of California Press. 1955.