@article{AMLG_1978__19_137951, author = {Georges Blanc}, title = {\'Equivalence naturelle et formules logiques en th\'eorie des cat\'egories.}, journal = {Archiv f\"ur mathematische Logik und Grundlagenforschung}, pages = {131--138}, publisher = {mathdoc}, volume = {19}, year = {1978}, zbl = {0407.03035}, url = {http://geodesic.mathdoc.fr/item/AMLG_1978__19_137951/} }