@article{JRAM_1964__0214_0215_150617,
     author = {Helmut Koch},
     title = {\"Uber den {2-Klassenk\"orperturm} eines quadratischen {Zahlk\"orpers.} {I.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {201--206},
     year = {1964},
     volume = {0214_0215},
     zbl = {0123.03904},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1964__0214_0215_150617/}
}