Józef Drewniak
- Aggregations Preserving Classes of Fuzzy Relations. KYBERNETIKA 41 (2005) n.3, 265-284.
- Preservation of Properties of Fuzzy Relations During Aggregation Processes. KYBERNETIKA 43 (2007) n.2, 115-132.
- Properties of Fuzzy Relations Powers. KYBERNETIKA 43 (2007) n.2, 133-142.