Cyril Bateman commented on Ed Simon's article on resistor non-linearity in Vol 1. Cyril recalled some vintage testequipment documentation and application notes for measuring passive device non-linearities. He has graciously provided PDF copies of these documents which can be accessed here:
Harmonic testing pinpoints passive component flaws”, Vilhelm Peterson and Per-Olof Harris, L.M. Ericsson Telephone Co., Stockholm; Electronics, July 1966, all rights reserved.
CLTI Component Linearity Test Equipment”, company literature and letter to Mr. Bateman
The Non-linearity of Fixed Resistors”, P. L. Kirby; Electronic Engineering, November 1965