Levens, A. S., Edstrom, A. E., & French, T. E. (1966). Problems in mechanical drawing: With emphasis on freehand sketching ([3d ed].). Webster Division, McGraw-hill.
Chicago Style (17th ed.) CitationLevens, Alexander Sander, Alfred E. Edstrom, and Thomas Ewing French. Problems in Mechanical Drawing: With Emphasis on Freehand Sketching. [3d ed]. St. Louis, Mo: Webster Division, McGraw-hill, 1966.
MLA (9th ed.) CitationLevens, Alexander Sander, et al. Problems in Mechanical Drawing: With Emphasis on Freehand Sketching. [3d ed]. Webster Division, McGraw-hill, 1966.
Warning: These citations may not always be 100% accurate.