This entry is about (the legendary conference Como 1990 and) the excellent proceedings volume

A. Carboni, M. Pedicchio, G. Rosolini, Category theory , Proceedings of the International Conference held in Como 1990, 213–236, Lecture Notes in Math. 1488, Springer (1991).

which is one of the overall historical heights of the (quality content of the) proceedings within the tradition of conferences in pure category theory. Now it is even hard to find a publisher for contemporary category conference proceedings…

S. Kasangian, S. Vigna, Trees in distributive categories, 237–248

A. Kock, Algebras for the partial map classifier monad, 262–278

F. W. Lawvere, Intrinsic co-Heyting boundaries and the Leibniz rule in certain toposes, 279–281

Duško Pavlović, Categorical interpolation: descent and the Beck-Chevalley condition without direct images, 306–325 ($n$lab remark: important clarification of the subject from logics point of view).

A. J. Power, An $n$-categorical pasting theorem, 326–58