@article{CTGDC_1977__18_1_61_0,
     author = {Perry, Robert J.},
     title = {An extended comparison functor for triples},
     journal = {Cahiers de topologie et g\'eom\'etrie diff\'erentielle},
     pages = {61--65},
     publisher = {Dunod \'editeur, publi\'e avec le concours du CNRS},
     volume = {18},
     number = {1},
     year = {1977},
     mrnumber = {444739},
     zbl = {0354.18006},
     language = {en},
     url = {http://www.numdam.org/item/CTGDC_1977__18_1_61_0/}
}