In answer to the question about sources for research/study on Tolkien and his works, I can recommend a few. The Inklings: C.S. Lewis, J.R.R. Tolkien, Charles Williams, and Their Friends by Humphrey Carpenter, Master of Middle-Earth: The Fiction of J.R.R. Tolkien by Paul H. Kocher, J.R.R. Tolkien: Architect of Middle-earth by Daniel Grotta-Kurska are three of the best. You already possess the biography of Tolkien by Carpenter, do you not? If so, with these suggestions you should do quite well.