Tuning A3-A4 Using a Checknote
The Real Deal (or as close as we can get on a computer). Tune A3A4 as a pure 4:2 by listening to the unfiltered M3/M10 test.
Your results will be posted here.
How to Tune Pianos
The Hobby, Skill, and Career of Piano Tuning
By Mark Cerisano