不知道为啥jstor也下不来呢？
The Erosion-Productivity Impact Calculator (EPIC) Model: A Case History
J. R. Williams
Philosophical Transactions: Biological Sciences
Vol. 329, No. 1255, Quantitative Theory is Soil Productivity and Environmental Pollution (Sep. 29, 1990), pp. 421-428
(article consists of 8 pages)
Published by: The Royal Society
Stable URL: http://www.jstor.org/stable/76847
先谢谢各位！