Williams K R. (1991). The natural calculator: Using the natural processes of the mind for mental calculation. Motilal Banarsidass.
استشهاد بنمط شيكاغوWilliams K R. The Natural Calculator: Using the Natural Processes of the Mind for Mental Calculation. New Delhi: Motilal Banarsidass, 1991.
MLA استشهادWilliams K R. The Natural Calculator: Using the Natural Processes of the Mind for Mental Calculation. Motilal Banarsidass, 1991.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.