@article{MZ_1975__145_172283, author = {Norman L. Johnson}, title = {Regularly {Derived} {Planes.}}, journal = {Mathematische Zeitschrift}, pages = {201--210}, year = {1975}, volume = {145}, zbl = {0322.50011}, url = {http://geodesic.mathdoc.fr/item/MZ_1975__145_172283/} }