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http://www.sciencedirect.com/science/article/pii/B9780081000229000050

http://www.sciencedirect.com/science/article/pii/S0167701208002054

http://www.sciencedirect.com/science/article/pii/S0168160507005740

http://www.sciencedirect.com/science/article/pii/S1156523309000456