@article{article, title = {{The theory of classification part 4: Object types and subtyping}}, url = {{https://eprints.whiterose.ac.uk/79278/ }}, year = {{2002}}, month = {{1}}, author = {{Simons AJH}}, doi = {{10.5381/jot.2002.1.5.c2}}, volume = {{1}}, journal = {{Journal of Object Technology}}, issue = {{5}}, pages = {{27-33}}, note = {{Accessed on 2025/06/02}}}