APA

(1976). Ecological Systems and the Environment. California - E.E.U.U: Houghton Mifflin Company.

Chicago

1976. Ecological Systems and the Environment. California - E.E.U.U: Houghton Mifflin Company.

Harvard

(1976). Ecological Systems and the Environment. California - E.E.U.U: Houghton Mifflin Company.

MLA

Ecological Systems and the Environment. California - E.E.U.U: Houghton Mifflin Company. 1976.