00289nam a2200097Ia 4500008004100000041000800041082001900049100001900068245009500087260000900182211209s1971    xx            000 0 und d  aeng  a515.62 N71 SPI  aSPIEGEL MURRAY  aSCHAUM'S THEORY AND PROBLEMS OF CALCULUS OF FINITE DIFFERENCES AND DIFFERENCIAL EQUATIONS   c1971