@article{GDZPPN002055945,
title = {A New Curvature Theory for Surfaces in a Euclidean 4-Space.},
journal = {Commentarii mathematici Helvetici},
volume = {26},
year = {1952},
pages = {152-170},
zbl = {0048.15102},
url = {http://dml.mathdoc.fr/item/GDZPPN002055945}
}
Wong, Yung-Chow. A New Curvature Theory for Surfaces in a Euclidean 4-Space.. Commentarii mathematici Helvetici, Tome 26 (1952) pp. 152-170. http://gdmltest.u-ga.fr/item/GDZPPN002055945/