1. M. A. Akivis, “On three-webs of multidimensional surfaces,” Itogi Nauki Tekh. Ser. Probl. Geom. Tr. Geom. Sem., 2, 7–31 (1969).
2. M. A. Akivis and A. M. Shelekhov, Multidimensional Three-Webs and Their Applications [in Russian], Tver, 2010.
3. W. Blaschke, Introduction to the Geometry of Webs [Russian translations], GIFML, Moscow (1959).
4. G. Bol, “¨Uber zwei Kurvenscharen und eine Flachenschar,” Abh. Math. Sem. Univ. Hamburg, 93–94 (1932).
5. S. S. Chern, “Eine Invariantentheorie der Dreigewebe aus r-dimensionalen Mannigfaltigkeiten in R 2r ,” Abh. Math. Sem. Univ. Hamburg, 11, No. 1, 2, 333–358 (1936).