[1] Chajda I.: On the tolerance extension property. Časop. pěst. mat. 103 (1978), 327-332. MR 0512228 | Zbl 0391.06008

[2] Chajda I., Niederle J., Zelinka B.: On existence conditions for compatible tolerances. Czech. Math. J. 26 (1976), 304-311. MR 0401561 | Zbl 0333.08006

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