[1] Chajda I.: Characterizations of relational bocks. Algebгa Univ. 10 (1980), 65-69. MR 0552157

[2] Chajda I.: Partitions, coverings and bocks of binary relations. Glasnik Matem. (Zagreb) 14 (1979), 21-26. MR 0544058

[3] Chajda I., Duda J.: Blocks of binary relations. Annales Univ. Sci. Budapest, sectio Math. 22 (1979). MR 0588416

[4] Chajda I., Zelinka B.: Lattices of compatible tolerances. Časop. pěst. matem. 102 (1977), 10-24. MR 0450152

[5] Chajda I., Zelinka B.: Compatible relations on algebras. Časop. pěst. matem. 100 (1975), 355-360. MR 0389710 | Zbl 0315.08004

[6] Grätzer G.: Universal Algebra. D. van Nostгand, N.Y. 1968. MR 0248066

[7] Maľcev A. I.: On the general theory of algebraic structures. (Russian), Matem. Sbornik 35 (1954), 3-20. MR 0065533

[8] Tzeng Chung-Hung, Tzeng O. Chun-Shun: Tolerance spaces and almost periodic functions. Bull. of the Inst. of Math. Acad. Sinica, Vol. 6, No. 1 (1978), 159-173. MR 0511074