@article{10_4064_aa139_2_2,
     author = {Zden\v{e}k Polick\'y},
     title = {On the group of circular units
 of any compositum of quadratic fields},
     journal = {Acta Arithmetica},
     pages = {111--115},
     publisher = {mathdoc},
     volume = {139},
     number = {2},
     year = {2009},
     doi = {10.4064/aa139-2-2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/aa139-2-2/}
}