@article{TAC_2006_16_a18,
     author = {Peter Freyd},
     title = {Numerology in topoi},
     journal = {Theory and applications of categories},
     pages = {522--528},
     publisher = {mathdoc},
     volume = {16},
     year = {2006},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/TAC_2006_16_a18/}
}