Howard Whitley Eves: Great Moments in Mathematics (before 1650). Mathematical Association of America, 1983, ISBN9780883853108, S. 37 (excerpt, p. 37, at Google Books)
Donchian, P. S.; Coxeter, H. S. M. (July 1935). "1142. An n-dimensional extension of Pythagoras' Theorem". The Mathematical Gazette. 19 (234): 206. doi:10.2307/3605876. JSTOR3605876. S2CID125391795.
Donald R Conant & William A Beyer (Mar 1974). "Generalized Pythagorean Theorem". The American Mathematical Monthly. 81 (3). Mathematical Association of America: 262–265. doi:10.2307/2319528. JSTOR2319528.
Kheyfits, Alexander (2004). "The Theorem of Cosines for Pyramids". The College Mathematics Journal. 35 (5). Mathematical Association of America: 385–388. doi:10.2307/4146849. JSTOR4146849.
Donchian, P. S.; Coxeter, H. S. M. (July 1935). "1142. An n-dimensional extension of Pythagoras' Theorem". The Mathematical Gazette. 19 (234): 206. doi:10.2307/3605876. JSTOR3605876. S2CID125391795.
Donald R Conant & William A Beyer (Mar 1974). "Generalized Pythagorean Theorem". The American Mathematical Monthly. 81 (3). Mathematical Association of America: 262–265. doi:10.2307/2319528. JSTOR2319528.
Kheyfits, Alexander (2004). "The Theorem of Cosines for Pyramids". The College Mathematics Journal. 35 (5). Mathematical Association of America: 385–388. doi:10.2307/4146849. JSTOR4146849.
Donchian, P. S.; Coxeter, H. S. M. (July 1935). "1142. An n-dimensional extension of Pythagoras' Theorem". The Mathematical Gazette. 19 (234): 206. doi:10.2307/3605876. JSTOR3605876. S2CID125391795.