@article{10_21136_MB_1997_126149,
     author = {Jurga, Rastislav},
     title = {The cross-ratio in {Hjelmslev} planes},
     journal = {Mathematica Bohemica},
     pages = {243--247},
     publisher = {mathdoc},
     volume = {122},
     number = {3},
     year = {1997},
     doi = {10.21136/MB.1997.126149},
     mrnumber = {1600879},
     zbl = {0901.51003},
     language = {en},
     url = {https://geodesic-test.mathdoc.fr/articles/10.21136/MB.1997.126149/}
}