@article{BSMF_1975__103__177_0,
     author = {Gras, Georges},
     title = {Crit\`ere de parit\'e du nombre de classes des extensions ab\'eliennes r\'eelles de $Q$ de degr\'e impair},
     journal = {Bulletin de la Soci\'et\'e Math\'ematique de France},
     pages = {177--190},
     publisher = {Soci\'et\'e math\'ematique de France},
     volume = {103},
     year = {1975},
     doi = {10.24033/bsmf.1800},
     mrnumber = {52 #8081},
     zbl = {0312.12013},
     language = {fr},
     url = {http://www.numdam.org/articles/10.24033/bsmf.1800/}
}