@article{MOMA_1975__80_177712,
     author = {Allan M. Krall},
     title = {On the {Solutions} of (ry')' + qy = f.},
     journal = {Monatshefte f\"ur Mathematik},
     pages = {115--118},
     publisher = {mathdoc},
     volume = {80},
     year = {1975},
     zbl = {0323.34029},
     url = {http://geodesic.mathdoc.fr/item/MOMA_1975__80_177712/}
}