@article{JRAM_1980__320_152297,
     author = {J.C. Lagarias},
     title = {Signatures of units and congruences (mod 4) in certain real quadratic fields. {II.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {115--126},
     publisher = {mathdoc},
     volume = {320},
     year = {1980},
     zbl = {0439.12004},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1980__320_152297/}
}