no. 4
The convexity of the subset space of a metric space
Compositio Mathematica, Tome 22 (1970) no. 4, pp. 383-385. 
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     author = {Bryant, V. W.},
     title = {The convexity of the subset space of a metric space},
     journal = {Compositio Mathematica},
     pages = {383--385},
     publisher = {Wolters-Noordhoff Publishing},
     volume = {22},
     number = {4},
     year = {1970},
     mrnumber = {275293},
     zbl = {0205.27102},
     language = {en},
     url = {http://archive.numdam.org/item/CM_1970__22_4_383_0/}
}
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Bryant, V. W. The convexity of the subset space of a metric space. Compositio Mathematica, Tome 22 (1970) no. 4, pp. 383-385. http://archive.numdam.org/item/CM_1970__22_4_383_0/

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