I've recently acquired a copy of Roy Bacon's "British Motorcycles of the 30's" from eBay at a bargain price. This complements his books on bikes of the 40's/50's and 60's I've also got. If you have any kind of interest in British bikes this series of books is must. They contain a vast amount of information & pictures. Yes I know the 60's book has a mid '70 Trident on the cover.