@article{JRAM_1990__412_153277,
     author = {S.M.J. Wilson},
     title = {A projective invariant comparing rings of integers in wildly ramified extensions.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {35--47},
     publisher = {mathdoc},
     volume = {412},
     year = {1990},
     zbl = {0713.11077},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1990__412_153277/}
}