@article{M2AN_1973__7_1_45_0,
     author = {Wood, Derick},
     title = {Bicolored digraph grammar systems},
     journal = {ESAIM: Mathematical Modelling and Numerical Analysis },
     pages = {45--52},
     publisher = {Dunod},
     address = {Paris},
     volume = {7},
     number = {R1},
     year = {1973},
     mrnumber = {388874},
     zbl = {0262.68014},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/M2AN_1973__7_1_45_0/}
}