Hoelscher, R. P., & Springer, C. H. (1961). Engineering drawing and geometry (2nd ed.). New York: John Wiley & Sons.
Παραπομπή Chicago StyleHoelscher, Randolph P., and Clifford H. Springer. Engineering Drawing and Geometry. 2nd ed. New York: John Wiley & Sons, 1961.
Παραπομπή MLAHoelscher, Randolph P., and Clifford H. Springer. Engineering Drawing and Geometry. 2nd ed. New York: John Wiley & Sons, 1961.
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