@InProceedings{PU99,
author    = {Hartmut Prautzsch and Georg Umlauf},
title     = {Improved triangular subdivision schemes},
booktitle = {Proceedings of the CGI '98},
year      = 1999,
editor    = {F.-E.~Wolter and N.M.~Patrikalakis},
pages     = {626-632}
}