1. Multiscale Symmetric Part Detection and Groupinghttp://www.maths.lth.se/matematiklth/personal/sminchis/papers/LevSminIccv2009.pdf
2. Multiscale Symmetric Part Detection and Grouping
3. Symmetry, Causality, Mind;Leyton,1992
4. Laws of organization in perceptual forms;Wertheimer,1938