Hartley, J. (1972). Strategies for programmed instruction: An educational technology. Butterworths.
Citazione stile Chigago Style (17a edizione)Hartley, J. Strategies for Programmed Instruction: An Educational Technology. London: Butterworths, 1972.
Citatione MLA (9a ed.)Hartley, J. Strategies for Programmed Instruction: An Educational Technology. Butterworths, 1972.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.