1. Introduction to bicategories;Bénabou,1967
2. Bicategorie di base;Betti;Istituto Matematico Milano,1980
3. Cauchy completion and the associated sheaf;Betti;Cahiers Topologie Géom. Différentielle,1982
4. Variation through enrichment;Betti;J. Pure Appl. Algebra,1983
5. R. Betti and R.F.C. Walters, Closed bicategories and variable category theory, to appear.