@article{CMH_1952__26_139042,
     author = {Yung-Chow Wong},
     title = {A {New} {Curvature} {Theory} for {Surfaces} in a {Euclidean} {4-Space.}},
     journal = {Commentarii mathematici Helvetici},
     pages = {152--170},
     publisher = {mathdoc},
     volume = {26},
     year = {1952},
     zbl = {0048.15102},
     url = {http://geodesic.mathdoc.fr/item/CMH_1952__26_139042/}
}