@article{oai:tsukuba.repo.nii.ac.jp:00033878,
 author = {星野, 光男 and Hoshino, Mitsuo and Kameyama, Noritsugu and Koga, Hirotaka},
 issue = {7},
 journal = {Journal of algebra and its applications},
 month = {Sep},
 note = {Let I be a nontrivial finite multiplicative group with the unit element e and A = ⨁x∈I Ax an I-graded ring. We construct a Frobenius extension Λ of A and study when the ring extension A of Ae can be a Frobenius extension. Also, formulating the ring structure of Λ, we introduce the notion of I-bigraded rings and show that every I-bigraded ring is isomorphic to the I-bigraded ring Λ constructed above.},
 title = {Group-graded and group-bigraded rings},
 volume = {14},
 year = {2015}
}