Cita APA (7a ed.)

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

Cita Chicago Style (17a ed.)

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

Cita MLA (9a ed.)

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