@article{AM2_1981__23_136912,
     author = {Kai Wang},
     title = {A generalization of group difference sets and the matrix equation {Am} = {dI} + {...J.}},
     journal = {Aequationes mathematicae},
     pages = {212--222},
     publisher = {mathdoc},
     volume = {23},
     year = {1981},
     zbl = {0504.05018},
     url = {http://geodesic.mathdoc.fr/item/AM2_1981__23_136912/}
}