NOTES. 
1. H. B. Porter, "Method And Means For Defining Contours From 
Stereoscopic Photographs." U. S. Patent No. 2,283,226, 
May 19, 1942. 
2. "Automatic Contouring Instrumentation," Report 1488-TR, 16 July 1957, 
U. S. Army Engineer Research And Development Laboratories, 
Fort Bel voir, Virginia. 
3. S. Bertram, "Automatic Map Compilation," Photogrammetric Engineer 
ing (January 19 63) . 
4. G. L. Hobrough, "Automatic Stereo," Report to the IXth International 
Congress of Photogrammetry, London, 1960. 
5. M. M. Birnbaum and Phil M. Salomon, "Correlation Circuit." 
U. S. Patent No. 3, 114,831, Dec. 17, 1963. 
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