Cita APA (7th ed.)

Duncan, D. J. (1979). Programmed learning aid for retailing: Modern concepts and ractices. Learning System.

Cita Chicago (17th ed.)

Duncan, Delbert J. Programmed Learning Aid for Retailing: Modern Concepts and Ractices. Homewood, III.: Learning System, 1979.

Cita MLA (9th ed.)

Duncan, Delbert J. Programmed Learning Aid for Retailing: Modern Concepts and Ractices. Learning System, 1979.