@article{GDZPPN002346915, title = {Planes of Curvature in Riemannian Spaces.}, journal = {Mathematica Scandinavica}, volume = {11}, year = {1962}, pages = {5-21}, zbl = {0121.38601}, url = {http://dml.mathdoc.fr/item/GDZPPN002346915} }
Eriksson, Folke. Planes of Curvature in Riemannian Spaces.. Mathematica Scandinavica, Tome 11 (1962) pp. 5-21. http://gdmltest.u-ga.fr/item/GDZPPN002346915/