Emmanuel Promayon Pierre Baconnier Claude Puech Physically-Based Deformations Constrained in Displacements and Volume. 155-164 1996 15 Comput. Graph. Forum 3 db/journals/cgf/cgf15.html#PromayonBP96 http://www.eg.org/EG/CGF/volume15/issue3/v15i3pp155-164_abstract.html