Bartha, Miklós. “On the Completeness of the Traced Monoidal Category Axioms in (Rel,+)”. Acta Cybernetica 23, no. 1 (January 1, 2017): 327-347. Accessed March 29, 2024. https://cyber.bibl.u-szeged.hu/index.php/actcybern/article/view/3928.