[2] J. Niederle: A note on tolerance lattices. Časop. pěst. matem. 107 (1982), 221-224. MR 0673045 | Zbl 0502.08004
[3] J. Niederle: On skeletal and irreducible elements in tolerance lattices of finite distributive lattices. Časop. pěst. matem. 107 (1982), 23-29. MR 0651079 | Zbl 0484.06015