@article{oai:tsukuba.repo.nii.ac.jp:00015799,
 author = {Nastasescu, C. and Torrecillas, B.},
 issue = {2},
 journal = {Tsukuba Journal of Mathematics},
 month = {Dec},
 pages = {461--479},
 title = {Graded coalgebras},
 volume = {17},
 year = {1993}
}