CCD lattices in presheaf categories. Cruttwell, G.S.H., Marmolejo, F., Wood, R.J. (2007) Theory and Applications of Categories [electronic only]
Congruence extension from a semilattice to the freely generated distributive lattice Isidore Fleischer (1982) Czechoslovak Mathematical Journal
Correction to the paper: A new look at pointfree metrization theorems Bernhard Banaschewski, Aleš Pultr (1998) Commentationes Mathematicae Universitatis Carolinae