APA (7e ed.) Bronvermelding

ENGEN, H. V. Foundations of elementary school arithmetic. Scott.

Chicago (17e ed.) Bronvermelding

ENGEN, Henry Van. Foundations of Elementary School Arithmetic. Chicago: Scott.

MLA (9e ed.) Bronvermelding

ENGEN, Henry Van. Foundations of Elementary School Arithmetic. Scott.

Let op: Deze citaties zijn niet altijd 100% accuraat.