@article{GDZPPN002195127,
title = {Signatures of units and congruences (mod 4) in certain real quadratic fields.},
journal = {Journal f\"ur die reine und angewandte Mathematik},
volume = {302},
year = {1978},
pages = {142-146},
zbl = {0375.12009},
url = {http://dml.mathdoc.fr/item/GDZPPN002195127}
}
Lagarias, J.C. Signatures of units and congruences (mod 4) in certain real quadratic fields.. Journal für die reine und angewandte Mathematik, Tome 302 (1978) pp. 142-146. http://gdmltest.u-ga.fr/item/GDZPPN002195127/