Cita APA (7a ed.)

Callahan, W. J. (1992). The Enneagram for Youth: Student edition. Loyola University.

Cita Chicago Style (17a ed.)

Callahan, William James. The Enneagram for Youth: Student Edition. Chicago: Loyola University, 1992.

Cita MLA (9a ed.)

Callahan, William James. The Enneagram for Youth: Student Edition. Loyola University, 1992.