000 00319nam a2200121 4500
008 160616s 000 0
245 _aSecond order equations with nonnegative characteristic form
100 _aOleinik, O.A
100 _aRadkevic, E>V
500 _aB334,1,1 L3
942 _cBK
_2BK3838
080 _a517.95 OLE
999 _c3838
_d3838