@article{JCA_1998_5_1_a10,
     author = {T. Nishishiraho},
     title = {Korovkin {Sets} and {Mean} {Ergodic} {Theorems}},
     journal = {Journal of convex analysis},
     pages = {147--152},
     publisher = {mathdoc},
     volume = {5},
     number = {1},
     year = {1998},
     url = {http://geodesic.mathdoc.fr/item/JCA_1998_5_1_a10/}
}