TY - JOUR T1 - The theory of classification part 6: The subtyping inquisition JO - Journal of Object Technology UR - https://eprints.whiterose.ac.uk/79271/ PY - 2003/01/01 AU - Simons AJH ED - DO - DOI: 10.5381/jot.2003.2.2.c2 VL - 2 IS - 2 SP - 17 EP - 26 Y2 - 2025/09/06 ER -