@article{CMUC_2007__48_4_a1,
     author = {Duffus, D. and Erd\"os, P. L. and Ne\v{s}et\v{r}il, J. and Soukup, L.},
     title = {Antichains in the homomorphism order of graphs},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {571--583},
     publisher = {mathdoc},
     volume = {48},
     number = {4},
     year = {2007},
     mrnumber = {2375159},
     zbl = {1199.06008},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_2007__48_4_a1/}
}