HELMER, R. G. (1991). Time Management For Engineers And Constructors Ray G. Helmer. American Society of Civil Engi.
Chicago-referens (17:e uppl.)HELMER, Ray Gray. Time Management For Engineers And Constructors Ray G. Helmer. American Society of Civil Engi, 1991.
MLA-referens (8:e uppl.)HELMER, Ray Gray. Time Management For Engineers And Constructors Ray G. Helmer. American Society of Civil Engi, 1991.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.