@article{DE_1970_6_8_a18,
     author = {Yu. I. Kovach and L. I. Savchenko},
     title = {The estimation of the solution of certain nonlinear integro-differential and operator equations with lag},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1496--1505},
     publisher = {mathdoc},
     volume = {6},
     number = {8},
     year = {1970},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1970_6_8_a18/}
}