@article{10_37236_10727,
     author = {Asaf Shapira},
     title = {Every orientation of a 4-chromatic graph has a non-bipartite acyclic subgraph},
     journal = {The electronic journal of combinatorics},
     year = {2022},
     volume = {29},
     number = {1},
     doi = {10.37236/10727},
     zbl = {1481.05054},
     url = {http://geodesic.mathdoc.fr/articles/10.37236/10727/}
}