Helmer, R. G. (1998). Time management: For engineers and constructors. American Society of Civil Engineers.
Cita Chicago (17th ed.)Helmer, Ray G. Time Management: For Engineers and Constructors. Washington, D.C: American Society of Civil Engineers, 1998.
Cita MLA (9th ed.)Helmer, Ray G. Time Management: For Engineers and Constructors. American Society of Civil Engineers, 1998.
Atenció: Aquestes cites poden no estar 100% correctes.