[1] Niederle J.: Relative bicomplements and tolerance extension property in distributive lattices. Časopis pěst. matem. 103 (1978), 250--254. MR 0505926 | Zbl 0393.06005

[2] Chajda I., Zelinka B.: Minimal compatible tolerances on lattices. Czech. Math. J. 27 (1977), 452-459. MR 0457300 | Zbl 0379.06002

[3] Chajda I.: Recent results and trends in tolerances on algebras and varieties. In: Colloquia Mathematica Societatis János Bolyai 28, North-Holland, Amsterdam 1981. MR 0648608 | Zbl 0484.08002