@article{MSH_1989__105__27_0,
     author = {Frey, Louis},
     title = {Besan\c{c}on : la porte noire. {Carr\'es} et diagonales},
     journal = {Math\'ematiques informatique et sciences humaines},
     pages = {27--62},
     publisher = {Ecole des hautes-\'etudes en sciences sociales},
     volume = {105},
     year = {1989},
     language = {fr},
     url = {http://www.numdam.org/item/MSH_1989__105__27_0/}
}