[1] Borůvka O.:
Grundlagen der Gruppoid- und Gruppentheorie. Berlin 1960.
MR 0117267
[2] Havel V.:
On semichained refinements of chains in equivalence lattice. Czech. Mat. Journ. 13 (1963), pp. 533-538.
MR 0157915 |
Zbl 0135.03102
[3] Janoš L.:
Properties of the Zassenhaus refinements. (in russian), Czech. Mat. Journ. 3 (1953), pp. 159-180.
MR 0060466
[4] Škrášek J.:
Application des méthodes mathématique a la theorie des clasifications. Publ. Fac. Sci. Univ. Brno, No 316, pp. 1-39 (1949).
MR 0039677