@article{oai:u-ryukyu.repo.nii.ac.jp:02005349,
 author = {Nishishiraho, Toshihiko and 西白保, 敏彦},
 journal = {Ryukyu mathematical journal},
 month = {Jan},
 note = {Korovkin closures for vector-valued functions are characterized by means of the technique of envelopes as well as the representing operators., 紀要論文},
 pages = {65--81},
 title = {Approximation of the Korovkin type for vector-valued functions},
 volume = {7},
 year = {1995}
}