Exceptional boundary points for the nondivergence equation which are regular for the Laplace equation - and vice-versa
Annali della Scuola Normale Superiore di Pisa - Classe di Scienze, Serie 3, Volume 22 (1968) no. 2, p. 315-330 
@article{ASNSP_1968_3_22_2_315_0,
     author = {Miller, Keith},
     title = {Exceptional boundary points for the nondivergence equation which are regular for the Laplace equation - and vice-versa},
     journal = {Annali della Scuola Normale Superiore di Pisa - Classe di Scienze},
     publisher = {Scuola normale superiore},
     volume = {Ser. 3, 22},
     number = {2},
     year = {1968},
     pages = {315-330},
     zbl = {0164.13102},
     mrnumber = {229961},
     language = {en},
     url = {http://www.numdam.org/item/ASNSP_1968_3_22_2_315_0}
}

Miller, Keith. Exceptional boundary points for the nondivergence equation which are regular for the Laplace equation - and vice-versa. Annali della Scuola Normale Superiore di Pisa - Classe di Scienze, Serie 3, Volume 22 (1968) no. 2, pp. 315-330. http://www.numdam.org/item/ASNSP_1968_3_22_2_315_0/

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