Heroic Worlds

This 1991 book by Lawrence Shick (author of S2 White Plume Mountain) is good resource for reading about products published during the era of Holmes Basic.

It's still in print at Amazon, where you can view a preview of the first 40 pages and the entire index.

HW is over 400 pages and has a paragraph for almost every RPG product prior to 1991. Not the most extensive info for each, but there are some nuggets (for example, I1 mentions that an early version of this module got Zeb Cook his job at TSR). There are also interesting short essays throughout the book by people like Gygax, Arneson, Moldvay. Plus it's got nice line art interspersed that is taken from the products in question (for example, the Lizardman from the Monster Manual).