Voir la notice de l'article provenant de la source Math-Net.Ru
@article{TRSPY_1964_73_a4, author = {K. K. Golovkin}, title = {Geometric smoothness characteristics of functions of two variables}, journal = {Informatics and Automation}, pages = {139--158}, publisher = {mathdoc}, volume = {73}, year = {1964}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/TRSPY_1964_73_a4/} }
K. K. Golovkin. Geometric smoothness characteristics of functions of two variables. Informatics and Automation, Boundary value problems of mathematical physics. Part 2, Tome 73 (1964), pp. 139-158. http://geodesic.mathdoc.fr/item/TRSPY_1964_73_a4/