TY - JOUR T1 - Specifying and Refining Internal Operations in Z JO - Formal Aspects of Computing PY - 1998/01/01 AU - Derrick J AU - Boiten E AU - Bowman H AU - Steen M ED - DO - DOI: 10.1007/s001650050007 VL - 10 IS - 2 SP - 125 EP - 159 Y2 - 2024/12/22 ER -