@article{AM2_1993__45_2-3_137527,
     author = {N.S. Papageorgiou},
     title = {On the },
     journal = {Aequationes mathematicae},
     pages = {267--280},
     publisher = {mathdoc},
     volume = {45},
     number = {2-3},
     year = {1993},
     zbl = {0780.34045},
     url = {http://geodesic.mathdoc.fr/item/AM2_1993__45_2-3_137527/}
}