@article{JRAM_1980__315_152227,
     author = {Ladislav Skula},
     title = {Index of irregularity of a prime.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {92--106},
     year = {1980},
     volume = {315},
     zbl = {0419.10016},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1980__315_152227/}
}