1. A. Day andR. Freese, A characterization of identities implying congruence modularity, Can. J. Math. (to appear).
2. R. Freese, Minimal modular congruence varieties, Abstract 76T-A14, Amer. Math. Soc. Notices 23 (1976) No. 1, A-4.
3. G. Hutchinson andG. Czédli, A test for identities satisfied in lattices of submodules, Algebra Univ.8 (1978), 269–309.
4. B. Jónsson, Congruence varieties, an appendix to G. Grätzer, Universal Algebra, 2nd edition.