Cita APA

(1989). Practice and reinforcement: (Blue level). New York: Mc Dougal, Littell & Company.

Chicago Style Citation

Practice and Reinforcement: (Blue Level). New York: Mc Dougal, Littell & Company, 1989.

Cita MLA

Practice and Reinforcement: (Blue Level). New York: Mc Dougal, Littell & Company, 1989.

Atenció: Aquestes cites poden no estar 100% correctes.