Document Type : Opinion
. (2011). . Mathematical Culture and Thought, 29(2), 79-81.
. "", Mathematical Culture and Thought, 29, 2, 2011, 79-81.
. (2011). '', Mathematical Culture and Thought, 29(2), pp. 79-81.
, "," Mathematical Culture and Thought, 29 2 (2011): 79-81,
. . An Expository Journal of the Iranian Mathematical Society. 2011;29(2):79-81 (In Persian).