Black Sea Scrolls, the Thanatosian Tomes, & Von Junzt's Unausprechlichen Kulten
All 3 of these are chronicles of the mystical dark doings in the Marvel Universe. What all 3 have in common is that they all tell of a cosmic obscenity that slumbers, but yet may awaken. These are believed to be references to Shuma-Gorath and were warnings of the Ancient One to Doctor Strange before he began stumbling upon the minions of "He Who Sleeps, But Will Awaken".
Other forbidden spells or references are contained within these chronicles. This does not necessarily mean that all the magic found within these works is chaotic magic, just that it was forbidden to be practiced at the time of the work's creation.