Não informado. (1970). Environmental quality. Council on Environmental Quality, Executive Office of the President.
Citação do estilo Chicago (17ª ed.)Não informado. Environmental Quality. Washington: Council on Environmental Quality, Executive Office of the President, 1970.
Citação MLA (8ª ed.)Não informado. Environmental Quality. Council on Environmental Quality, Executive Office of the President, 1970.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.
