Não informado. (1979). Focus on Learning Problems in Mathematics. Center for Teaching Learning on Mathematics.
শিকাগো স্টাইল (17 তম সংস্করণ) উদ্ধৃতিNão informado. Focus on Learning Problems in Mathematics. Framingham, Mass: Center for Teaching Learning on Mathematics, 1979.
M.L.A (8 ম সংস্করণ) উদ্ধৃতিNão informado. Focus on Learning Problems in Mathematics. Center for Teaching Learning on Mathematics, 1979.
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