@article{JRAM_1978__301_152024,
     author = {J.C. Lagarias},
     title = {Signatures of units and congruences (mod 4) in certain real quadratic fields.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {142--146},
     publisher = {mathdoc},
     volume = {301},
     year = {1978},
     zbl = {0375.12009},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1978__301_152024/}
}