On the Hölder continuity of weak solutions of quasilinear elliptic systems of second order
Annali della Scuola Normale Superiore di Pisa - Classe di Scienze, Serie 4, Volume 4 (1977) no. 1, p. 145-178 
@article{ASNSP_1977_4_4_1_145_0,
     author = {Hildebrandt, Stefan and Widman, Kjell-Ove},
     title = {On the H\"older continuity of weak solutions of quasilinear elliptic systems of second order},
     journal = {Annali della Scuola Normale Superiore di Pisa - Classe di Scienze},
     publisher = {Scuola normale superiore},
     volume = {Ser. 4, 4},
     number = {1},
     year = {1977},
     pages = {145-178},
     zbl = {0353.35013},
     mrnumber = {457936},
     language = {en},
     url = {http://www.numdam.org/item/ASNSP_1977_4_4_1_145_0}
}

Hildebrandt, Stefan; Widman, Kjell-Ove. On the Hölder continuity of weak solutions of quasilinear elliptic systems of second order. Annali della Scuola Normale Superiore di Pisa - Classe di Scienze, Serie 4, Volume 4 (1977) no. 1, pp. 145-178. http://www.numdam.org/item/ASNSP_1977_4_4_1_145_0/

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