Electronic circuit schematics, manuals, books, datasheets. Since Y2K.

Data Sheets

Electron valve / vacuum-tube datasheets.

Schematics

Audio equipment galore including schematics from Schematic-Heaven; professional and consumer electronics; guitar amplifiers and effects pedals, etc. Over half-a-million schematics and technical pages detail many thousands of products. All files curated and manicured.