Duncan, D. J. (1979). Programmed learning aid for retailing: Modern concepts and ractices. Learning System.
Citazione stile Chigago Style (17a edizione)Duncan, Delbert J. Programmed Learning Aid for Retailing: Modern Concepts and Ractices. Homewood, III.: Learning System, 1979.
Citatione MLA (9a ed.)Duncan, Delbert J. Programmed Learning Aid for Retailing: Modern Concepts and Ractices. Learning System, 1979.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.