@article{EUG_1987_14_a9,
     author = {B. G. Pachpatte},
     title = {Integral {Perturbations} of {Nonlinear} {Systems} of {Differential} {Equations}},
     journal = {E\ensuremath{\upsilon}\ensuremath{\kappa}\ensuremath{\lambda}\ensuremath{\varepsilon}\ensuremath{\acute\iota}\ensuremath{\delta}\ensuremath{\eta}\ensuremath{\varsigma} \ensuremath{\Gamma}},
     pages = {92--97},
     year = {1987},
     volume = {14},
     language = {gr},
     url = {http://geodesic.mathdoc.fr/item/EUG_1987_14_a9/}
}