Hazard, William J. (1929), "Generalizations of the Theorem of Pythagoras and Euclid's Theorem of the Gnomon", The American Mathematical Monthly, 36 (1): 32–34, doi:10.1080/00029890.1929.11986904, JSTOR2300175
Hazard, William J. (1929), "Generalizations of the Theorem of Pythagoras and Euclid's Theorem of the Gnomon", The American Mathematical Monthly, 36 (1): 32–34, doi:10.1080/00029890.1929.11986904, JSTOR2300175