Gaya APA

Billstein, R., W, I, L, S, I, L, J. (NULL). A Problem Solving Approach to Mathematics for Elementary School Teachers . California:: California: The Benjamin/Cummings Publishing; 1990.

Gaya MLA

Billstein, Rick., W, I., Libeskind,, Shlomo, II., Lott,, Johnny. "A Problem Solving Approach to Mathematics for Elementary School Teachers". California:: California: The Benjamin/Cummings Publishing; 1990, NULL. Text.