00293nam a2200109 a 450000500170000002000150001708200190003210000270005124500520007826000310013030000220016120251203091858.0  a0697204561  a363.7,bD, cun  aCunningham, William P.  aUnderstanding our environment : an introduction  aDubuquebWm.C. Brownc1994  axviii, 390p, 26cm