Merparten av amerikanska hifi/Audio-magasin från 30-70 tal finns scannad här: http://www.americanradiohistory.com/index.htm Gå in under rubriken Technical engineering och sedan Audio & Sound.
"The total harmonic distortion is not a measure of the degree of distastefulness to the listener and it is recommended that its use should be discontinued", Radiotron 3rd edition.