@article{00821697,
title = {An equichordal characterization of round spheres.},
journal = {Beitr\"age zur Algebra und Geometrie},
volume = {36},
year = {1995},
pages = {299-301},
zbl = {0833.53007},
language = {en},
url = {http://dml.mathdoc.fr/item/00821697}
}
Craveiro de Carvalho, Francisco José. An equichordal characterization of round spheres.. Beiträge zur Algebra und Geometrie, Tome 36 (1995) pp. 299-301. http://gdmltest.u-ga.fr/item/00821697/