@article{10_4064_aa119_3_2,
     author = {Tommy B\"ulow},
     title = {Relative norms of units and 4-rank of class groups},
     journal = {Acta Arithmetica},
     pages = {243--264},
     publisher = {mathdoc},
     volume = {119},
     number = {3},
     year = {2005},
     doi = {10.4064/aa119-3-2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/aa119-3-2/}
}