Environmental Education Project (Portland, Or.). (1978). Clearing. Environmental Education Project.
Cita Chicago (17th ed.)Environmental Education Project (Portland, Or.). Clearing. Portland, Or.: Environmental Education Project, 1978.
Cita MLA (9th ed.)Environmental Education Project (Portland, Or.). Clearing. Environmental Education Project, 1978.
Atenció: Aquestes cites poden no estar 100% correctes.