In November 1999, "Drizzt Do'Urden's Guide to the Underdark" (1999), by Eric L. Boyd, was released. Appelcline wrote that it "is the single-most comprehensive sourcebook on the realms of the Underdark that lie beneath the "Sword Coast". It talks about the major peoples of the Underworld and details dozens of cities, including Menzoberranzan" and that "Boyd's extensive research results in "Underdark" being full of tiny references. For example, drow cities are drawn from the list in "Drow of the Underdark" and from obscure references in "Menzoberranzan"".