Não informado. (1968). Professional Engineer. National Society of Professional Engineers.
Citação do estilo Chicago (17ª ed.)Não informado. Professional Engineer. Jersey City, NJ: National Society of Professional Engineers, 1968.
Citação MLA (8ª ed.)Não informado. Professional Engineer. National Society of Professional Engineers, 1968.
Предупреждение: эти цитированмия не могут быть всегда правильны на 100%.