Duncan, D. J. (1974). Programmed learning aid for retailing: Modern concepts and practices. Learning Systems Company.
Цитирование в стиле Чикаго (17-е изд.)Duncan, Delbert J. Programmed Learning Aid for Retailing: Modern Concepts and Practices. Homewood, Illinois: Learning Systems Company, 1974.
Цитирование MLA (9-е изд.)Duncan, Delbert J. Programmed Learning Aid for Retailing: Modern Concepts and Practices. Learning Systems Company, 1974.
Предупреждение: эти цитированмия не могут быть всегда правильны на 100%.