00264nam a2200109Ia 4500082001900000100001700019245006300036260003200099300001300131500000500144700000500149  a515.35bK29.DE  aKells, L. M.  aDifferential equations; a brief course with applicationsb  aNew YorkbMcGraw-Hillc1968  ax, 252p.  a  a