Kaihuai Qin Sun Jiaguang Xuefu Wang Representing Conics using NURBS of Degree Two. 285-291 1992 11 Comput. Graph. Forum 5 http://www.eg.org/EG/CGF/Volume11/Issue5/v11i5pp285-291_abstract.html db/journals/cgf/cgf11.html#QinJW92