@article{10_4153_CJM_1987_009_x,
     author = {Barr, Michael and Makkai, Michael},
     title = {On {Representations} of {Grothendieck} {Toposes}},
     journal = {Canadian journal of mathematics},
     pages = {168--221},
     year = {1987},
     volume = {39},
     number = {1},
     doi = {10.4153/CJM-1987-009-x},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1987-009-x/}
}