Mostly sourcebooks, IE: Not actual novels but written books, articles and such that go into detail, rather than a story like say... the Darth Bane books, or Shadows of the Empire, or any other series.
Just read the article. I believe it's basically mentioned, and even if it's not in THAT particular article, they have an article about each form and the basic concepts of lightsaber combat.
The Wiki articles are far more convenient in getting information over reading the actual books, if you ask me.