H.  Spies, Kirchgeßner, N., Scharr, H., and Jähne, B., ?Dense structure estimation via regularised optical flow?, in VMV 2000, 2000, p. 57--64.

H.  Haußecker and Jähne, B., ?A tensor approach for local structure analysis in multi-dimensional images?, in 3D Image Analysis and Synthesis, 1996, p. 171--178.