no. 1
The regularity of the trace for minimal surfaces
Annali della Scuola Normale Superiore di Pisa - Classe di Scienze, Série 4, Tome 3 (1976) no. 1, pp. 139-155. 
@article{ASNSP_1976_4_3_1_139_0,
     author = {Nitsche, Johannes C. C.},
     title = {The regularity of the trace for minimal surfaces},
     journal = {Annali della Scuola Normale Superiore di Pisa - Classe di Scienze},
     pages = {139--155},
     publisher = {Scuola normale superiore},
     volume = {Ser. 4, 3},
     number = {1},
     year = {1976},
     zbl = {0331.53006},
     mrnumber = {402624},
     language = {en},
     url = {archive.numdam.org/item/ASNSP_1976_4_3_1_139_0/}
}
Nitsche, Johannes C. C. The regularity of the trace for minimal surfaces. Annali della Scuola Normale Superiore di Pisa - Classe di Scienze, Série 4, Tome 3 (1976) no. 1, pp. 139-155. http://archive.numdam.org/item/ASNSP_1976_4_3_1_139_0/

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