@article{GMJ_2000__7_2_48669,
     author = {Qi, Aiqin and Liu, Yansheng},
     title = {Monotone iterative techniques and a periodic boundary value problem for first-order differential equations with a functional argument.},
     journal = {Georgian mathematical journal},
     pages = {373--378},
     year = {2000},
     volume = {7},
     number = {2},
     zbl = {0957.34065},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/GMJ_2000__7_2_48669/}
}