Tomás Feder, Pavol Hell, Bojan Mohar. Acyclic Homomorphisms and Circular Colorings of Digraphs. SIAM J. Discrete Math., 17(1):161-169, 2003. [doi]
@article{FederHM03,
title = {Acyclic Homomorphisms and Circular Colorings of Digraphs},
author = {Tomás Feder and Pavol Hell and Bojan Mohar},
year = {2003},
url = {http://epubs.siam.org/sam-bin/dbq/article/42218},
researchr = {https://researchr.org/publication/FederHM03},
cites = {0},
citedby = {0},
journal = {SIAM J. Discrete Math.},
volume = {17},
number = {1},
pages = {161-169},
}