[Ver, de casi más de 100 fuentes similares: Aristóteles, "Problemas", Libro XIX.10-13, Helmholtz "The Sensations of Tone"; Jeans, "Science & Music"; - a https://web.archive.org/web/20070212134229/http://www.percepp.demon.co.uk/pythagor.htm Robin Allot, "Las Bases Biológicas de la Música".]