Lectures, V. o. A. F. (1968). The quality of man's environment. Voice of America Forum Lectures.
Chicago-viite (17. p.)Lectures, Voice of America Forum. The Quality of Man's Environment. Voice of America Forum Lectures, 1968.
MLA-viite (8. p.)Lectures, Voice of America Forum. The Quality of Man's Environment. Voice of America Forum Lectures, 1968.
Varoitus: Nämä viitteet eivät aina ole täysin luotettavia.