3Hsieh, P. A.. Documenlation of a computer program to simulate horizontal - flow barriers using the U. S. Geological Survey modular three- dimensional finite - difference ground - water flow model[ R ]. Washington: U. S. Geological Survey Open - File Report,1993,92 - 477.
4McDonald, M. G.. A method of converting no - flow ceils to variable- head cells for the U. S. Geological Survey modular finite -difference groundwater flow model [ R ]. Washington: U. S. Geological Survey Open- File Report, 1992,91 -536.
5Hill, M.C. Solving groundwater flow problems by conjugate -Sradient methods and the strongly implicit procedure [J]. Water Resources Research, 1990,26 ( 9 ) : 1961-1969.
