@article{ARM_1972__8_4_a2,
     author = {Bebernes, J. and Schmitt, K.},
     title = {An existence theorem for periodic boundary value problems for systems of second order diffferential equations},
     journal = {Archivum mathematicum},
     pages = {173--176},
     publisher = {mathdoc},
     volume = {08},
     number = {4},
     year = {1972},
     mrnumber = {0335926},
     zbl = {0284.34016},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ARM_1972__8_4_a2/}
}