1[12]Karl G·Hempel and Paul Oppenheim:Studies in the Logic Of explanation Philosophy of Science,XV(April,1948),P.135~175.
2[13]Mcclelland:Causal Explanation and Modelbuilding in History,Economics,and the New Economic History,Cornell University Press,1975,P.41,45,47,59-60,93,111,128,151.