@article{JRAM_1914__144_149417,
     author = {Oskar Perron},
     title = {Absch\"atzung der {L\"osung} der {Pellschen} {Gleichung.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {71--73},
     publisher = {mathdoc},
     volume = {144},
     year = {1914},
     zbl = {45.0298.01},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1914__144_149417/}
}