Voir la notice de l'article provenant de la source Math-Net.Ru
@article{IVM_1965_5_a12, author = {\"U. G. Lumiste}, title = {The middle surface of congruences for planes in affine space}, journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika}, pages = {86--98}, publisher = {mathdoc}, number = {5}, year = {1965}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/IVM_1965_5_a12/} }
Ü. G. Lumiste. The middle surface of congruences for planes in affine space. Izvestiâ vysših učebnyh zavedenij. Matematika, no. 5 (1965), pp. 86-98. http://geodesic.mathdoc.fr/item/IVM_1965_5_a12/