"Mirror Racing" by Guy Wilkins, published by Fernhurst Books in 1989, ISBN 0 906754 45 3 and no longer in print. This book is a guide to making the most of this spectacularly popular boat. Using photo-sequences and diagrams, Guy Wilkins describes how to make your Mirror the quickest on the water - if necessary by building a new one - and explains how to fit it out and sail it fast on all legs of the course and in all conditions.
You may be able to find a second hand copy from a on-line bookshop, E-Bay or Amazon etc.