@article{CMUC_1997__38_1_a10,
     author = {Ne\v{s}et\v{r}il, J. and Sopena, E. and Vignal, L.},
     title = {$T$-preserving homomorphisms of oriented graphs},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {125--136},
     publisher = {mathdoc},
     volume = {38},
     number = {1},
     year = {1997},
     mrnumber = {1455476},
     zbl = {0886.05062},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1997__38_1_a10/}
}