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Twocolumnproof.png (437 × 404 pixels, file size: 156 KB, MIME type: image/png)
Description: Taken from Patricio G. Herbst, "Establishing a Custom of Proving in American School Geometry: Evolution of the Two-Column Proof in the Early Twentieth Century", Educational Studies in Mathematics, Vol. 49, No. 3 (2002), pp. 283-312. Herbst says, "Photographed by the author from Schulze and Sevenoak, 1913, p. 53, Macmillan publishers." This paper is available from http://www.jstor.org/stable/3483034
Usage Terms: Public domain
License: Public domain
Attribution Required?: No