@article{MAN_1973__206_162522,
     author = {Raymond W. Freese},
     title = {A 2-metric {Characterization} of the {Euclidean} {Plane.}},
     journal = {Mathematische Annalen},
     pages = {285--294},
     year = {1973},
     volume = {206},
     zbl = {0252.50001},
     url = {http://geodesic.mathdoc.fr/item/MAN_1973__206_162522/}
}