1. How It Works?https://www.tronicaltune.com/how-it-works
2. The Theory of Sound;Rayleigh,1945
3. Manual of Guitar Technology: The History and Technology of Plucked String Instruments;Jahnel,1981
4. Viscoelastic properties of nylon guitar strings;Chaigne;Catgut Acoust. Soc. J.,1991