@article{PetzKastenProhaskaetal.2009, author = {Christoph Petz and Jens Kasten and Steffen Prohaska and Hans-Christian Hege}, title = {Hierarchical Vortex Regions in Swirling Flow}, journal = {Computer Graphics Forum}, volume = {28}, number = {3}, pages = {863 -- 870}, year = {2009}, }