@article{CMUC_1993_34_3_a1,
     author = {Liz, E. and Nieto, Juan J.},
     title = {The monotone iterative technique for periodic boundary value problems  of second order impulsive differential equations},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {405--411},
     year = {1993},
     volume = {34},
     number = {3},
     mrnumber = {1243071},
     zbl = {0780.34006},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1993_34_3_a1/}
}