MRH discusses HM.
Milton R. Hunter, The Gospel Through the Ages (Salt Lake City: Deseret Book Co., 1945), 98-99
The stupendous truth of the existence of a Heavenly Mother, as well as a Heavenly Father, became established facts in Mormon theology. A complete realization that we are the offspring of Heavenly Parents--that we are begotten and born into the spirit world and grew to maturity in that realm--became an integral part of Mormon philosophy. Those verities are basic in the Gospel plan of eternal progression.