@article{10_4064_aa_85_3_249_263, author = {Tsutomu Shimada}, title = {Index for subgroups of the group of units in number fields}, journal = {Acta Arithmetica}, pages = {249--263}, publisher = {mathdoc}, volume = {85}, number = {3}, year = {1998}, doi = {10.4064/aa-85-3-249-263}, language = {en}, url = {http://geodesic.mathdoc.fr/articles/10.4064/aa-85-3-249-263/} }