@article{00821691,
title = {On a characterization of circles and spheres.},
journal = {Beitr\"age zur Algebra und Geometrie},
volume = {36},
year = {1995},
pages = {211-218},
zbl = {0844.52003},
language = {en},
url = {http://dml.mathdoc.fr/item/00821691}
}
Groemer, H. On a characterization of circles and spheres.. Beiträge zur Algebra und Geometrie, Tome 36 (1995) pp. 211-218. http://gdmltest.u-ga.fr/item/00821691/