Παραπομπή σε μορφή APA (7η εκδ.)

HELMER, R. G. (1991). Time Management For Engineers And Constructors Ray G. Helmer. American Society of Civil Engi.

Παραπομπή σε μορφή Chicago (17η εκδ.)

HELMER, Ray Gray. Time Management For Engineers And Constructors Ray G. Helmer. American Society of Civil Engi, 1991.

Παραπομπή σε μορφή MLA (8th εκδ.)

HELMER, Ray Gray. Time Management For Engineers And Constructors Ray G. Helmer. American Society of Civil Engi, 1991.