@article{MAN_1976__220_162825,
     author = {Marvi W. Grossman},
     title = {Korovkin {Theorems} for {Adapted} {Spaces} with {Respect} to a {Positive} {Operator.}},
     journal = {Mathematische Annalen},
     pages = {253--262},
     publisher = {mathdoc},
     volume = {220},
     year = {1976},
     zbl = {0308.41018},
     url = {http://geodesic.mathdoc.fr/item/MAN_1976__220_162825/}
}