@article{MASLO_1984_34_1_a1,
     author = {H{\'\i}c, Pavol},
     title = {On partially directed $P$-graphs},
     journal = {Mathematica slovaca},
     pages = {25--34},
     year = {1984},
     volume = {34},
     number = {1},
     mrnumber = {735935},
     zbl = {0608.05037},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/MASLO_1984_34_1_a1/}
}