@article{AM2_1989__37_2-3_137304,
     author = {Joseph Zaks},
     title = {On four-colourings of the rational four-space.},
     journal = {Aequationes mathematicae},
     pages = {259--266},
     publisher = {mathdoc},
     volume = {37},
     number = {2-3},
     year = {1989},
     zbl = {0705.05033},
     url = {http://geodesic.mathdoc.fr/item/AM2_1989__37_2-3_137304/}
}