@article{JRAM_1950__188_150179,
     author = {Paul Armsen},
     title = {\"Uber die {Strahlenbrechung} an einer einfachen {Sammellinse.} {II.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {65--73},
     publisher = {mathdoc},
     volume = {188},
     year = {1950},
     zbl = {0038.39501},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1950__188_150179/}
}