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@article{MAT_1966_10_6_a2, author = {V. Pt\'ak}, title = {A combinatorial lemma on the existence of convex means and its application to weak compactness}, journal = {Matematika}, pages = {44--59}, publisher = {mathdoc}, volume = {10}, number = {6}, year = {1966}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/MAT_1966_10_6_a2/} }
V. Pták. A combinatorial lemma on the existence of convex means and its application to weak compactness. Matematika, Tome 10 (1966) no. 6, pp. 44-59. http://geodesic.mathdoc.fr/item/MAT_1966_10_6_a2/