Vetter, T Department Human Perception, Cognition and Action, Max Planck Institute for Biological Cybernetics, Max Planck Society; Max Planck Institute for Biological Cybernetics, Max Planck Society;
https://brill.com/view/journals/sv/8/4/article-p443_5.xml (Publisher version)
Vetter, T., & Poggio, T. (1994). Symmetric 3D objects are an easy case for 2D object recognition. Spatial Vision, 8(4), 443-453. doi:10.1163/156856894X00107.