@article{10_1017_S0017089500008661,
     author = {Choe, Boo Rim},
     title = {The essential norms of composition operators},
     journal = {Glasgow mathematical journal},
     pages = {143--155},
     year = {1992},
     volume = {34},
     number = {2},
     doi = {10.1017/S0017089500008661},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500008661/}
}