1. M. A. Akivis, ?On a local differentiable quasigroup and a three-web which are defined by a triple of hypersurfaces? Sibirsk. Matem. Zh.,14, No. 3, 467?474 (1973).
2. G. F. Laptev, ?Differential geometry of imbedded manifolds,? Trudy Moskov. Matem. Obshch.,2, 275?382 (1953).
3. M. A. Akivis and A. M. Shelekhov, ?On local differentiable quasigroups and connections associated with a three-web of multidimensional surfaces,? Sibirsk. Matem. Zh.,12, No. 6, 1181?1191 (1971).
4. B. A. Rozenfel'd, Multidimensional Spaces [in Russian], Nauka, Moscow (1966).
5. M. A. Akivis, ?On three-webs of multidimensional surfaces,? Trudy Geom. Seminara,2, 7?31 (1969).