The following publications are possibly variants of this publication:
- The Theory of Classification, Part 7: A Class is a Type FamilyAnthony J. H. Simons. jot, 2(3):13-22, 2003. [doi]
- The Theory of Classification, Part 11: Adding Class Types to Object ImplementationsAnthony J. H. Simons. jot, 3(3):7-19, 2004. [doi]
- The Theory of Classification, Part 16: Rules of Extension and the Typing of InheritanceAnthony J. H. Simons. jot, 4(1):13-26, 2005. [doi]
- The Theory of Classification, Part 4: Object Types and SubtypingAnthony J. H. Simons. jot, 1(5):27-35, 2002. [doi]