I suggest these all from personal experience and success (yes, these books have indirectly made me money):

* Tom Hopkins - How To Master The Art Of Selling (some of it is a bit American but the overall concepts learned here are priceless)

* Harry Beckwith - What Clients Want

* Leil Lowndes - How to Talk to Anyone (not directly sales, but this is a massive part of it nonetheless)

* Sam Horn - POP! Stand Out In Any Crowd (this will help you hone your message - learning to sell is good, but if your message sucks, so will the selling)

All of these are reasonably short, cpl hundred pages at most.