Convexity of balls and fixed-point theorems for mappings with nonexpansive square
Compositio Mathematica, Volume 22 (1970) no. 3, p. 269-274
@article{CM_1970__22_3_269_0,
author = {Goebel, K.},
title = {Convexity of balls and fixed-point theorems for mappings with nonexpansive square},
journal = {Compositio Mathematica},
publisher = {Wolters-Noordhoff Publishing},
volume = {22},
number = {3},
year = {1970},
pages = {269-274},
zbl = {0202.12802},
mrnumber = {273477},
language = {en},
url = {http://www.numdam.org/item/CM_1970__22_3_269_0}
}

Goebel, K. Convexity of balls and fixed-point theorems for mappings with nonexpansive square. Compositio Mathematica, Volume 22 (1970) no. 3, pp. 269-274. http://www.numdam.org/item/CM_1970__22_3_269_0/

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