A veritable smorgasbord of historical articles is maintanted and still being extended by Douglas Self. Especially his Wireless World section of articles is priceless, but in general his site has lots of interesting info.
Audio design leaps forward? Giovanni Stochino, EW&WW, Oct 1994.
Amplifier design for low Transient Intermodulation Distortion - Matti Otala's Low Tim Amplifier from AES preprint H-6(R) from Feb 1973
Several vintage documents on thermal distortion in power stages, resulting from signal-related die temperature changes. Also called 'memory distortion': 'La distorsion thermique' Part I, Part II, by Héphaïtos (from L'Audiophile, 1984), and 'Amplifier transient crossover distortion resulting from temperature change of output power transistors', AES preprint 1896 (October 1982)
"Class B in a new class" by Mike Renardson, Electronics World April 1998.
A classical amplifier in the mid-70-ies was the 'Barney amplifier'. Designed by Barney Oliver at HP, and manufactured, tested and documented as a regular HP piece of equipment. The Tech- & User Manual is here. A gem!