@article{AMLG_1981__21_137985, author = {Michael v. Rimscha}, title = {Universality and strong extensionality.}, journal = {Archiv f\"ur mathematische Logik und Grundlagenforschung}, pages = {179--194}, year = {1981}, volume = {21}, zbl = {0481.03031}, url = {http://geodesic.mathdoc.fr/item/AMLG_1981__21_137985/} }