@article{CTGDC_1995__36_1_3_0,
     author = {Barr, Michael and Pedicchio, M. Cristina},
     title = {$Top^{op}$ is a quasi-variety},
     journal = {Cahiers de Topologie et G\'eom\'etrie Diff\'erentielle Cat\'egoriques},
     pages = {3--10},
     publisher = {Dunod \'editeur, publi\'e avec le concours du CNRS},
     volume = {36},
     number = {1},
     year = {1995},
     mrnumber = {1322799},
     zbl = {0819.18002},
     language = {en},
     url = {http://www.numdam.org/item/CTGDC_1995__36_1_3_0/}
}