1. A few more incomplete self-orthogonal Latin squares and related designs;Abel;Austral. J. Combin.,2000
2. r-Orthogonal quasigroups I;Belyavskaya;Math Issled.,1976
3. r-Orthogonal quasigroups II;Belyavskaya;Math Issled.,1977
4. G.B. Belyavskaya, r-Orthogonal Latin squares, in: J. Dénes, A.D. Keedwell (Eds.), Latin Squares: New Developments, Elsevier, North-Holland, Amsterdam, 1992, pp. 169–202 (Chapter 6).
5. The spectrum of r-Orthogonal Latin squares;Colbourn,1995