[1] BIRKHOFF G.: Lattice Theory. Amer. Math. Soc. Colloq. Publ. Vol. 25, Amer. Math. Soc., Providence, R.I., 1967. MR 0227053 | Zbl 0153.02501

[2] CHAJDA I., RACHŮNEK J.: Forbidden configurations for distributive and modular ordered sets. Order 5 (1989), 407-423. MR 1010389 | Zbl 0674.06003

[3] KOLIBIAR M.: Linien in Verbänden. An. Ştiinţ. Univ. "Al. I. Cuza" Iaşi Secţ. I a Mat. (N.S.) XIB (1965), 89-98. MR 0201353 | Zbl 0151.01603