@article{10_4064_ba61_3_1,
     author = {A. Schinzel},
     title = {Extensions of {Three} {Theorems} of {Nagell}},
     journal = {Bulletin of the Polish Academy of Sciences. Mathematics},
     pages = {195--200},
     year = {2013},
     volume = {61},
     number = {3},
     doi = {10.4064/ba61-3-1},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ba61-3-1/}
}