Mason, R. D. (1978). Programmed learning aid for business and consumer mathematics. Learning Systems.
Lua i Stíl Chicago (17ú heag.)Mason, Robert D. Programmed Learning Aid for Business and Consumer Mathematics. Homewood, Ill: Learning Systems, 1978.
Lua MLA (9ú heag.)Mason, Robert D. Programmed Learning Aid for Business and Consumer Mathematics. Learning Systems, 1978.
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