I used to have a set of those, back in the day. I seem to recall they were made by someone tracing out the motherboard... the official manuals weren't available to the users, unless you knew a service shop. I sold my set a long time ago.... but since in the meantime, I became a service guy, I could get the "official" set.
Edit: Here's an ad from a 1986 AmigaWorld... I couldn't find a review.
