Patricia A. McKillip's "The Forgotten Beasts of Eld" and Jane Yolen's "The Magic Three of Solatia" were two examples of Tolkien-inspired fantasies for young adults written in the mid-1970s. Ballantine, under the direction of editor Lin Carter, published public domain and relatively obscure works under the banner of the Ballantine Adult Fantasy series, aimed at adult readers who enjoyed Tolkien's works. Lester Del Rey, however, sought for new books that would mirror Tolkien's work, and published Terry Brooks' "The Sword of Shannara", David Eddings's "Belgariad", and Stephen R. Donaldson's "The Chronicles of Thomas Covenant, the Unbeliever". Guy Gavriel Kay, who had assisted Christopher Tolkien with the editing of "The Silmarillion", later wrote his own Tolkien-influenced fantasy trilogy, "The Fionavar Tapestry". Russian writer Nick Perumov was able to publish several fantasy novels set in Tolkien's Middle-Earth after the events of "The Lord of the Rings" (due to a loophole in Russian copyright law). Dennis L. McKiernan's Silver Call duology was intended to be a direct sequel to "The Lord of the Rings" but had to be altered. The "Iron Tower" trilogy, highly influenced by Tolkien's books, was then written as backstory.