Complex sentence: Elminster was one of the first characters Greenwood created for the "Forgotten Realms"; information about him can be found in virtually all game products, but "The Elminster Series" of novels by Greenwood are perhaps the most definitive sources of information.
Split into simpler sentences: Elminster was one of the first characters that Greenwood created for the "Forgotten Realms". Information about him can be found in virtually all game products, but "The Elminster Series" of novels by Greenwood are perhaps the most definitive sources of information.