1. J. Adámek, H. Herrlich, G.E. Strecker, Abstract and Concrete Categories: The Joy of Cats, online version of a book first published by Wiley, New York, 1990, http://katmat.math.uni-bremen.de/acc/acc.pdf.
2. Adjonctions et monades au niveau des 2-catégories;Auderset;Cahiers de Topologie et Géométrie Différentielle,1974
3. Doi–Hopf modules, Yetter–Drinfeld modules and Frobenius type properties;Caenepeel;Transactions of the American Mathematical Society,1997
4. Matrices, relations and group representations;Carboni;Journal of Algebra,1991
5. Cartesian bicategories I;Carboni;Journal of Pure and Applied Algebra,1987