@article{MZ_1976__151_172434,
     author = {Choo-whan Kim},
     title = {Extreme {Contraction} {Operators} on l...},
     journal = {Mathematische Zeitschrift},
     pages = {101--110},
     publisher = {mathdoc},
     volume = {151},
     year = {1976},
     zbl = {0321.47025},
     url = {http://geodesic.mathdoc.fr/item/MZ_1976__151_172434/}
}