[1] BENADO M.: Les ensembles partiellement ordonnees et le theoreme de Schreier II. Czechoslovak Math. J. 5 (1955), 308-344. MR 0076744

[2] BIRKHOFF G.: Lattice Theory. Colloquium Publications, Vol. XXV, Amer. Math. Soc., Providence, RI, 1967. MR 0227053 | Zbl 0153.02501

[3] GRATZER G.: Universal Algebra. D. Van Nostrand Company, Inc., Princeton, 1968. MR 0248066

[4] GRATZER G.: General Lattice Theory. Akademie Verlag, Berlin, 1978. MR 0504338

[5] HALAS R.: Decompositions of directed sets with zero. Math. Slovaca 45 (1995), 9-17. MR 1335835 | Zbl 0833.06001

[6] HASHIMOTO J.: On direct product decompositions of partially ordered sets. Ann. of Math. (2) 54 (1951), 315-318. MR 0043067

[7] JAKUBÍK J.: Weak product decompositions of discrete lattices. Czechoslovak Math. J. 21 (1971), 399-412. MR 0286723 | Zbl 0224.06003

[8] JAKUBÍK J.: Weak product decompositions of partially ordered sets. Colloq. Math. 25 (1972), 13-26. MR 0329977

[9] JAKUBÍK J.-CSONTOOVA M.: Convex isomorphisms of directed multilattices. Math. Bohem. 118 (1993), 359-374. MR 1251882 | Zbl 0802.06008

[10] JAKUBÍK J.-CSONTOOVA M.: Cancellation rule for internal direct product decompositions of a connected partially ordered set. Math. Bohem. 125 (2000), 115-122. MR 1752083 | Zbl 0967.06001

[11] KOLIBIAR M.: Graph isomorphisms of semilattices. In: Contributions to General Algebra 3, Proc. Vienna Conference, 1984, Verlag Holder-Pichler-Temspsky, Wien, 1985, pp. 225-235. MR 0815129

[12] PRINGEROVA G.: Direct product decompositions of a directed set. Acta Fac. Paed. Univ. Safarik 17 (1996), 1-8. (Slovak)