Billstein, R. (1987). A problem solving approach to mathematics for elementary school teachers (3rd ed.). Benjamin/Cummings.
Citazione stile Chigago Style (17a edizione)Billstein, Rick. A Problem Solving Approach to Mathematics for Elementary School Teachers. 3rd ed. Menlo Park, Calif: Benjamin/Cummings, 1987.
Citatione MLA (9a ed.)Billstein, Rick. A Problem Solving Approach to Mathematics for Elementary School Teachers. 3rd ed. Benjamin/Cummings, 1987.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.