APA

Levens A. S., . (1957). Problems in mechanical drawing. New York: McGraw-Hill.

Chicago

Levens Alexander Sander, . 1957. Problems in mechanical drawing. New York: McGraw-Hill.

Harvard

Levens A. S., . (1957). Problems in mechanical drawing. New York: McGraw-Hill.

MLA

Levens Alexander Sander, . Problems in mechanical drawing. New York: McGraw-Hill. 1957.