Cita APA (7th ed.)

Ackoff, R. L., & Emery, F. E. (1972). On purposeful systems. Tavistock Publications.

Cita Chicago (17th ed.)

Ackoff, Russell Lincoln, i F. E. Emery. On Purposeful Systems. London: Tavistock Publications, 1972.

Cita MLA (9th ed.)

Ackoff, Russell Lincoln, i F. E. Emery. On Purposeful Systems. Tavistock Publications, 1972.