Martin Aigner Bert Jüttler Laureano González-Vega Josef Schicho Parameterizing surfaces with certain special support functions, including offsets of quadrics and rationally supported surfaces. 180-191 2009 44 J. Symb. Comput. 2 http://dx.doi.org/10.1016/j.jsc.2008.08.001 db/journals/jsc/jsc44.html#AignerJGS09