A. M. Onishchenko, Yu. A. Onishchenko, “Increase of Reliability of Control and Recognition of Patterns. II. Systematization of Patterns by Standard Definitions of Normal Two-Dimensional Sets”, Avtomat. i Telemekh., 1996, no. 8, 67–77; Autom. Remote Control, 57:8 (1996), 1118–1126
