Further works authorized by the Tolkien Estate include "The History of The Hobbit" in two volumes by John D. Rateliff and "The Annotated Hobbit" by Douglas A. Anderson, both with notes and early drafts by Tolkien. Linguistic material by Tolkien concerning Middle-earth has also been published with the permission of the Estate in two periodical publications. The Qenya and Gnomish Lexicons, in full, appear in "Parma Eldalamberon" Numbers 11–16; other mostly self-contained fragments, notes, and poems appear in various issues of "Vinyar Tengwar". All of this material together constitutes a collection which, much like real-world histories and mythologies, contains numerous points of obscurity, omission, or apparent contradiction.