Não informado. (1972). Ecological Research Series. U.S. Environmental Protection Agency.
Chicago-viite (17. p.)Não informado. Ecological Research Series. Washington: U.S. Environmental Protection Agency, 1972.
MLA-viite (8. p.)Não informado. Ecological Research Series. U.S. Environmental Protection Agency, 1972.
Varoitus: Nämä viitteet eivät aina ole täysin luotettavia.