Erné, Marcel: Distributive laws for concept lattices. In: Algebra Universalis, 30 (1993), S. 538-580
Grätzer, George ; Lakser, Henry: On Complete Congruence Lattices of Complete Lattices. In: Trans. Amer. Math. Soc., 327 (1991), Nr. 1, S. 385--405
Hales, A. W.: On the non-existence of free complete Boolean algebras. In: Fundamentae Mathematica, 54 (1964), S. 45-66