Toposes, Triples and Theories. By Michael Barr and Charles Wells
Category Theory for Computing Science, by Michael Barr and Charles Wells.
Handbook of Mathematical Discourse, by Charles Wells.
"Communicating Mathematics: Useful Ideas from Computer Science" , by Charles Wells
"Communicating Logical Reasoning" , by Atish Bagchi and Charles Wells
"Varieties of Mathematical Prose" by Atish Bagchi and Charles Wells
“Extension theories for monoids” (updated with corrections and references to citations)
“Graph based logic and sketches” (with Atish Bagchi)
“On the limitations of sketches” (with Michael Barr)
"Sketches: Outline with references". With updates.
Some applications of the wreath product construction, American Mathematical Monthly 83 (1976), 317-338.
Centralizers of transitive semigroup actions and endomorphisms of trees, Pacific Journal of Mathematics 64 (1976), 165-271.
A Krohn-Rhodes Theorem for categories, Journal of Algebra 64 (1980), 37-45.
A triple in Cat, Proceedings of the Edinburgh Mathematical Society 23 (1980), 261- 268.
The formal description of data types using sketches (with Michael Barr). In M. Main et al, ed., Mathematical Foundations of Programming Language Semantics. Lecture Notes in Computer Science 298. Springer-Verlag (1988).
Wreath product decomposition of categories I and II. Acta Sci. Math. Szeged 52 (1988), 307-319 and 321-324.
A formalism for the specification of essentially-algebraic structures in 2-categories (with A. J. Power). Mathematical Structures in Computer Science 2 (1992), 1-28. (with Michael Barr)