53 kvint
- https://en.wikipedia.org/wiki/53_equal_temperament
- https://en.wikipedia.org/wiki/Five-limit_tuning
- http://ripnread.com/listen/sing53-c5-slow.mp3
- http://www.math.uwaterloo.ca/~mrubinst/tuning/12.html
- https://letterstonature.wordpress.com/2008/05/23/the-imperfection-of-the-musical-scale-part-1/
- https://letterstonature.wordpress.com/2008/06/08/the-imperfection-of-the-musical-scale-part-2/
- https://hubpages.com/entertainment/tuning-systems