1. R.N. Nagel and Rosenfeld, “Steps toward Handwritten Signature Verification”, First International Joint Conference on Pattern Recognition, Washington D.C., 1973
2. W.F. Nemcek and W.C. Lin, “Experimental Investigation of Automatic Signature Verification”, IEEE Transactions on Systems, Man and Cybernetics, January 1974
3. P.C. Chuang, “Machine Verification of Handwritten Signature Image”, Proceedings of the 1977 International Conference on Crime Countermeasures — Science and Engineering, Juli 1977
4. B. Rieger, „Skelettierungsverfahren für die automatische Schreibererkennung“, im gleichen Band
5. Fukunaga, “Introduction to Statistical Pattern Recognition”, Academic Press, New York and London, 1972