@article{AFM_1983_8_1_a8,
     author = {J. Appel},
     title = {Upper estimates for superposition operators and some applications},
     journal = {Annales Fennici Mathematici},
     pages = {149--159},
     publisher = {mathdoc},
     volume = {8},
     number = {1},
     year = {1983},
     doi = {10.5186/aasfm.1983.0803},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.5186/aasfm.1983.0803/}
}