Boolean Extensions and Normal Subdirect Powers of Finite Universal Algebras. Matthew I. Gould; George Grätzer — 1967 Mathematische Zeitschrift
Tolerances, covering systems, and the axiom of choice George Grätzer; Günter H. Wenzel — 1989 Archivum Mathematicum
Congruence representations of join-homomorphisms of distributive lattices: a short proof George Grätzer; Harry Lakser; E. Tamás Schmidt — 1996 Mathematica Slovaca