1. J. Adámek H. Herrlich G. E. Strecker Abstract and Concrete Categories (John Wiley & Sons, Inc., New York - Chichester- Brisbane - Toronto - Singapore, 1990).
2. Structures algebriques dans les categories;Bénabou;Cahiers Topologie Géom. Différentielle,1968
3. G. Birkhoff Lattice Theory, American Mathematical Society Colloquium Publications Vol. 25 (Amer. Math. Soc., Providence, RI, 1973).
4. Heterogeneous algebras;Birkhoff;J. Combin. Theory,1970
5. Representation of lattices by sets;Birkhoff;Trans. Amer. Math. Soc.,1948