00448nam a2200157   450000500170000000700040001700800040002104000090002505000210003410000190005524500700007425000320014426000480017630000240022465000420024820150417152355.0000000  aUOEL  aQA372b.C36 1962  aCohen, Abraham  aAn elementary treatise on differential equations /cAbraham Cohen  a2nd ed.bcompletely revised  aBoston ;bD. C. Heath and Company ,cc1962.  avii, 337 p. :bill.  aDifferential - equationsxMathematics