@article{CMJ_1999__49_4_a18,
     author = {Ibrahim, Sobhy El-sayed},
     title = {On $L^2_w$-quasi-derivatives for solutions of perturbed general quasi-differential equations},
     journal = {Czechoslovak Mathematical Journal},
     pages = {877--890},
     publisher = {mathdoc},
     volume = {49},
     number = {4},
     year = {1999},
     mrnumber = {1746713},
     zbl = {1015.34002},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMJ_1999__49_4_a18/}
}