00346nam a2200133 a 450000500170000010000250001724500320004226000240007430000100009896400230010899700120013199900170014395200520016020251203090705.0  aThornbury,William D.  aPrinciples of Geomorphology  aWiley Easternc1985  a594p.  bENGLISHcdefg_  a20379 W  c16503d16503  02104070aPUbPUd1998-08-28l0o p20379yBK