00570 a2200181 4500 068972 OSt 20250926114000.0 518.64 C76S Constanda, Christian Solution techniques for elementary partial differential equations By Christian Constanda 2nd ed. New York Crc Press 2010 xxiii; 325p. Pbk Differential equations, Partial--Numerical solutions; Differential equations, Partial ddc BK 28975 28975