@article{MZ_1974__139_172108,
     author = {Toshihiko Yamada},
     title = {The {Schur} {Subgroup} of a {Real} {Cyclotomic} {Field.}},
     journal = {Mathematische Zeitschrift},
     pages = {35--44},
     publisher = {mathdoc},
     volume = {139},
     year = {1974},
     zbl = {0278.12002},
     url = {http://geodesic.mathdoc.fr/item/MZ_1974__139_172108/}
}