A Transformation for Extracting New Descriptors of Shape
Harry Blum.
Models for the Perception of Speech and Visual Form, MIT Press, Weiant Wathen-Dunn, pp. 362--380, Cambridge,
1967. [BibTeX]
The notion of quantitative invisibility and the machine rendering solids
Arthur Appel.
Proceedings of the 22nd ACM National Conference, pp. 387--393, Washington, D.C., United States, ACM Press,
1967. [BibTeX]