There are all kinds of books on Mormon doctrine. "Mormon" is a nickname for members of The Church of Jesus Christ of Latter-day Saints. The church itself is also often called the Mormon Church. Despite the nickname, the church is Christian and has some very similar doctrines to other Christian denominations.
Still, there are certain Mormon doctrines that are unique and which require a bit deeper study of reliable material to gain a good understanding of. I have been a Mormon all of my life and, while I feel I have a good grasp of all the basic doctrines of the Church, I still thoroughly enjoy studying and learning even more.
Many Christian denominations use only the Bible in their canon. The Mormon Church, however, as a canon of four standards works which include the Bible, the Book of Mormon, the Doctrine and Covenants, and the Pearl of Great Price. There are some misconceptions that the Book of Mormon is the "Mormon Bible." Mormons use the King James Version of the Bible, a highly respected translation. The Book of Mormon is meant to be a companion to the Bible rather than a replacement for it; in fact, its subtitle is "Another Testament of Jesus Christ." The Doctrine and Covenants is a collection of modern revelations and the Pearl of Great Price contains translations of earlier texts which supplement the Bible.
In addition to the Standards Works, there are many books which are not considered scripture which can still help anyone wishing to learn more about Mormon doctrine. Hugh Nibley was a renowned Mormon and Biblical scholar, and he has several publications which one could study multiple times and continue learning from. Also, many church leaders have published works of their own. Again, these works should not be taken as scripture, but can still offer valuable insights and resources to someone wanting to gain a deeper understanding of some aspect of Mormon doctrine.
The Church of Jesus Christ of Latter-day Saints also has several magazines which are published monthly and which are valuable resources. The three main publications are the Friend, which is written for children; the New Era, which is written for teenagers and young adults; and the Ensign, which is written for adults. Each of these magazines contains material which helps people stay connected with others of the same faith. They also prove valuable tools for Church leaders to communicate with Church members.
My parents always had these magazines for us growing up, but it was only when I went away to college that I really started reading the Ensign, but I have come to appreciate and love this magazine. The stories from other members are inspiring and comforting and give me strength in my own trials.
I love to learn more about the gospel of Jesus Christ through study and faith. I have learned a good deal about Mormon doctrine through personal study, Sunday school, religion courses at college, and discussions with other people. There are many valuable resources available.