First off, do a search on Google or Yahoo with "3-view" and the name of your plane. You'll be surprised what you might turn up with that simple step alone.
Here's a site in Russia that has a bunch of 3-views:
MkMagazin
And another:
site
If you need to order 3-views, I swear by
Bob's Aircraft Documentation They have something on just about everything that flies with fixed wings, although quality varies. But, at least they have good guides so you know what quality you're likely to get.
The other route to go is to find Profile Publication pamphlets on ebay or Maru Mechanic (
/!\ these are in Kanji, although the diagrams speak for themselves and are usually understandable even if you don't speak any Japanese!
/!\).