Citazione Stile APA (7a Edizione)

Mock, V. E. (1982). Subtraction drill for levels 1-3. David S. Lake Publishers.

Citazione stile Chigago Style (17a edizione)

Mock, Valerie E. Subtraction Drill for Levels 1-3. Belmont, Calif: David S. Lake Publishers, 1982.

Citatione MLA (9a ed.)

Mock, Valerie E. Subtraction Drill for Levels 1-3. David S. Lake Publishers, 1982.