APA

(1982). Geologic maps: portraits of the earth. Washington D.C: U.S. Dept. of the Interior, Geological Survey.

Chicago

1982. Geologic maps: portraits of the earth. Washington D.C: U.S. Dept. of the Interior, Geological Survey.

Harvard

(1982). Geologic maps: portraits of the earth. Washington D.C: U.S. Dept. of the Interior, Geological Survey.

MLA

Geologic maps: portraits of the earth. Washington D.C: U.S. Dept. of the Interior, Geological Survey. 1982.