Cita APA (7th ed.)

Johnson, D. W., Johnson, R. T., & Holubec, E. J. (1990). Circles of learning: Cooperation in the classroom (3rd ed.). Interaction Book.

Cita Chicago (17th ed.)

Johnson, David W., Roger T. Johnson, i Edythe Johnson Holubec. Circles of Learning: Cooperation in the Classroom. 3rd ed. Edina, Minn: Interaction Book, 1990.

Cita MLA (9th ed.)

Johnson, David W., et al. Circles of Learning: Cooperation in the Classroom. 3rd ed. Interaction Book, 1990.