@article{GDZPPN002305429, title = {On a Theorem of Fenchel-Borsuk-Willmore-Chern-Lashof.}, journal = {Mathematische Annalen}, volume = {193}, year = {1971}, pages = {19-26}, zbl = {0211.53602}, url = {http://dml.mathdoc.fr/item/GDZPPN002305429} }
CHEN, Bang-Yen. On a Theorem of Fenchel-Borsuk-Willmore-Chern-Lashof.. Mathematische Annalen, Tome 193 (1971) pp. 19-26. http://gdmltest.u-ga.fr/item/GDZPPN002305429/