Levens, A. S., & Eggers, H. C. T. (1941). Descriptive geometry. Harper.
Cita Chicago (17th ed.)Levens, A. S., i H. C. T. Eggers. Descriptive Geometry. New York: Harper, 1941.
Cita MLA (9th ed.)Levens, A. S., i H. C. T. Eggers. Descriptive Geometry. Harper, 1941.
Atenció: Aquestes cites poden no estar 100% correctes.