no. 2
Some open problems on best approximation in normed linear spaces
Séminaire Choquet. Initiation à l'analyse, Tome 6 (1966-1967) no. 2, Exposé no. 12, 8 p. 
@article{SC_1966-1967__6_2_A2_0,
     author = {Singer, Ivan},
     title = {Some open problems on best approximation in normed linear spaces},
     journal = {S\'eminaire Choquet. Initiation \`a l'analyse},
     note = {talk:12},
     pages = {1--8},
     publisher = {Secr\'etariat math\'ematique},
     volume = {6},
     number = {2},
     year = {1966-1967},
     mrnumber = {235369},
     zbl = {0172.16105},
     language = {en},
     url = {http://www.numdam.org/item/SC_1966-1967__6_2_A2_0/}
}
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Singer, Ivan. Some open problems on best approximation in normed linear spaces. Séminaire Choquet. Initiation à l'analyse, Tome 6 (1966-1967) no. 2, Exposé no. 12, 8 p. http://www.numdam.org/item/SC_1966-1967__6_2_A2_0/

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