@article{CMUC_2005__46_3_a17,
     author = {Polick\'y, Zden\v{e}k},
     title = {Diophantine equation $\frac{q^n-1}{q-1}=y$ for four prime divisors of $y-1$},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {577--588},
     publisher = {mathdoc},
     volume = {46},
     number = {3},
     year = {2005},
     mrnumber = {2174534},
     zbl = {1121.11031},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_2005__46_3_a17/}
}