1. Subspace Methods of Pattern Recognition;Oja,1983
2. Subspace method of pattern recognition;Watanabe,1973
3. Digital Picture Processing;Rosenfeld,1976
4. A new video-thresholding method for recognition of low quality stamped alphanumerals;Nakano;Trans. IEICE, Part D,1986
5. Stamped character inspection apparatus base on the bit matrix method;Hongo,1982