00262nam a2200109Ia 4500008004100000041000800041082001900049100001800068245004900086260000900135300000800144211209s1971    xx            000 0 und d  aeng  a515.45 N71 PET  aPETROVSKY I G  aLECTURES ON THE THEORY OF INTEGRAL EQUATION   c1971  a135