Butts, T. (1973). Problem solving in mathematics: Elementary number theory and arithmetic. Scott, Foresman and Company.
Chicago-referens (17:e uppl.)Butts, Thomas. Problem Solving in Mathematics: Elementary Number Theory and Arithmetic. Glenview, Illinois: Scott, Foresman and Company, 1973.
MLA-referens (9:e uppl.)Butts, Thomas. Problem Solving in Mathematics: Elementary Number Theory and Arithmetic. Scott, Foresman and Company, 1973.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.