@article{MAN_1959__137_160690,
     author = {H. Schaefer},
     title = {\"Uber algebraische {Integralgleichungen} mit nichtnegativen {Koeffizienten.}},
     journal = {Mathematische Annalen},
     pages = {385--391},
     publisher = {mathdoc},
     volume = {137},
     year = {1959},
     zbl = {0107.31604},
     url = {http://geodesic.mathdoc.fr/item/MAN_1959__137_160690/}
}