APA (7e ed.) Bronvermelding

Barnett-Clarke, C., & Ramirez, A. (2003). Number sense and operations in the primary grades: Hard to teach and hard to learnn. Heinemann.

Chicago (17e ed.) Bronvermelding

Barnett-Clarke, Carne, en Alma Ramirez. Number Sense and Operations in the Primary Grades: Hard to Teach and Hard to Learnn. Portsmouth, N.H: Heinemann, 2003.

MLA (9e ed.) Bronvermelding

Barnett-Clarke, Carne, en Alma Ramirez. Number Sense and Operations in the Primary Grades: Hard to Teach and Hard to Learnn. Heinemann, 2003.