Interesting little book on eBay, going by the name of The Second Book of the Lambretta – LI and TV models by RH Warring.
Very few details on the site, as it seems to be a charity selling it rather than a scooter enthusiast. But you can probably gather than it's a reference book on those particular scooter models, written 'back in the day'. Indeed, some inside shots show both diagrams and photos.
Just 99 pence right now.
Find out more at the eBay website
Update: just spotted this interesting scootering paperback book too. It's by Jon Stevens and is being sold by the same people. Also 99 pence.