Cita APA (7th ed.)

Ellsworth, B., Higgins, J. A., & Keller, A. (2002). Exercises for English simplified (4th Canadian ed.). Longman.

Cita Chicago (17th ed.)

Ellsworth, Blanche, John A. Higgins, i Arnold Keller. Exercises for English Simplified. 4th Canadian ed. Toronto: Longman, 2002.

Cita MLA (9th ed.)

Ellsworth, Blanche, et al. Exercises for English Simplified. 4th Canadian ed. Longman, 2002.