clymer is what I use not expensive,, had to get one for the 4 stroke skies and they were not available from clymer, sea doo charged about 100 ,, granted it is a better book than clymer,, but it's 3 times the cost.
A year ago I down loaded a seadoo service manual for my gtx, off of a pwc site. Don't remeber witch one, do some google searches and you'll have a nice maunal. I'd send it to you but its 45megs