Noble 1927, pp.286–293. Noble, Charles A. (1927). "The Teaching of Mathematics in German Secondary Schools and the Training of Teachers for These Schools". The American Mathematical Monthly. 34 (6): 286–293. doi:10.1080/00029890.1927.11986705. ISSN0002-9890.
Noble 1927, pp.286–293. Noble, Charles A. (1927). "The Teaching of Mathematics in German Secondary Schools and the Training of Teachers for These Schools". The American Mathematical Monthly. 34 (6): 286–293. doi:10.1080/00029890.1927.11986705. ISSN0002-9890.