@article {204,
	title = {A G^1 and a G^2 subdivision scheme for trinagular nets},
	journal = {International Journal on Shape Modelling},
	volume = {6},
	year = {2000},
	pages = {21-35},
	author = {Hartmut Prautzsch and Georg Umlauf}
}
@article {205,
	title = {A G^2 subdivision algorithm},
	journal = {Computing},
	volume = {13},
	year = {1998},
	pages = {217-224},
	author = {Hartmut Prautzsch and Georg Umlauf}
}
