APA-referens (7:e uppl.)

Butler, C. H. 1., & Wren, F. L. 1. (1960). The teaching of secondary mathematics (3d ed.). McGraw-Hill.

Chicago-referens (17:e uppl.)

Butler, Charles H. 1894, och Frank Lynwood 1894 Wren. The Teaching of Secondary Mathematics. 3d ed. New York: McGraw-Hill, 1960.

MLA-referens (9:e uppl.)

Butler, Charles H. 1894, och Frank Lynwood 1894 Wren. The Teaching of Secondary Mathematics. 3d ed. McGraw-Hill, 1960.