[1] ADAMS M. E., KELLY D.: 
Chain conditions in free products of lattices. Algebra Univ., 7, 1977, 235-243. 
MR 0434894 | 
Zbl 0358.06014 
[2] BALBES R., HORN A.: 
Order sums of distributive lattices. Pacif. J. of Math., 21, 1967, 421-435. 
MR 0211928 | 
Zbl 0157.34401 
[3] DEAN R. A.: 
Free lattices generated by partially ordered sets and preserving bounds. Canad. J. Math., 16, 1964, 136-148. 
MR 0157916 | 
Zbl 0122.25801 
[4] GRÄTZER G.: 
Universal Algebra. London 1968. 
MR 0248066 
[5] GRÄTZER G., LAKSER H.: 
Free-lattice-like sublattices of free product of lattices. Proc. Amer. Math. Soc., 44, 1974, 43-45. 
MR 0327591 
[6] GRÄTZER G., LAKSER H., PLATT C. R.: 
Free products of lattices. Fundam. Math., 69, 1970, 233-240. 
MR 0274351 | 
Zbl 0206.29703 
[7] GRÄTZER G., SICHLER J.: 
Free decomposition of a lattice. Canad. J. Math., 27, 1975, 276-285. 
MR 0369195 
[8] HÖFT M.: 
The order sum in classes of partially ordered algebras. J. für die reine und angewandte Math., 278/279, 1975, 78-92. 
MR 0389709 | 
Zbl 0325.08002 
[9] JÓNSSON B.: 
Relatively free products of lattices. Algebra Univ., 1, 1971, 362-373. 
MR 0300946 
[10] KUCERA T. G., SANDS B.: 
Lattices of lattice homomoprhisms. Algebra Univ., 8, 1978, 180-190. 
MR 0463056 
[11] LADZIANSKA Z.: 
Poproduct of lattices and Sorkin's theorem. Mat. čas., 24, 1974, 247-252. 
MR 0354460 | 
Zbl 0288.06005 
[12] LADZIANSKA Z.: 
Chain conditions in the distributive poproduct of lattices. Mat. čas., 24, 1974, 349-356. 
MR 0384631 
[13] LAKSER H.: 
Normal and canonical representations in free products of lattices. Canad. J. Math., 22, 1970, 394-402. 
MR 0265232 | 
Zbl 0288.06004 
[14] SORKIN, J I.: Svobodnye obedinenija struktur. Mat. sb. 30, 1952, 677-694.