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gravity model

Posted by liuqx315 on 13 Jun 2011 at 15:11 GMT

After I read this paper, I feel that it is a interesting work. However, I have a confuse about the Gravity models. The Gravity models idea seems borrow from original literature by Yingcun Xia and Ottar N. Bjørnstad and Bryan T. Grenfell vol. 164, no. 2 the American naturalist, but they does't give any hint.

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