@article{GDZPPN002481065, title = {Quasiregular Points and Time Changes.}, journal = {Monatshefte f\"ur Mathematik}, volume = {85}, year = {1978}, pages = {245-252}, zbl = {0398.28022}, url = {http://dml.mathdoc.fr/item/GDZPPN002481065} }
Veech, William A. Quasiregular Points and Time Changes.. Monatshefte für Mathematik, Tome 85 (1978) pp. 245-252. http://gdmltest.u-ga.fr/item/GDZPPN002481065/