00271nam a2200145Ia 450000500170000002000090001708200110002610000170003724500140005425000080006826000260007630000080010250000090011065000060011920250725171526.0  aNULL  a591.88  aWelch, P. S. 0aLimnology  a2nd  aNew YorkbMcgraw Hill  a538  a1311  a-