Sumner, W. L. (1938). Teaching of arithmetic and elementary mathematics. Blackwell.
Citazione stile Chigago Style (17a edizione)Sumner, William Leslie. Teaching of Arithmetic and Elementary Mathematics. London: Blackwell, 1938.
Citatione MLA (8a ed.)Sumner, William Leslie. Teaching of Arithmetic and Elementary Mathematics. Blackwell, 1938.
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