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Many of the early leaders of the Mormon church, such as Sidney Rigdon, were formerly associated with various Campbellite groups, from which the modern day Disciples of Christ and Churches of Christ derive. Campbellism grew out of largely Baptist and Presbyterian origins, but with the defectors to the movement rejecting Calvinist doctrines of total depravity, limited atonement, and irresistible grace and believing that the movement was a restoration of the primitive church rather than a correction of the errors of medieval Catholicism. The Campbellite churches remained in the pale of orthodoxy insofar as they are trinitarian, recognize the Substitutionary Atonement of Christ as the only acceptable payment for sins, see faith in Christ as Savior as the only means of salvation, and believe in the general resurrection at the end of this age. They are Protestant (though many Campbellites would deny this) because they adhere to the "solas" of the Reformation (except for the belief, most prevalent in the Churches of Christ, that water baptism by a Campbellite minister is necessary for salvation).

As noted previously, the LDS church drew many of its early leaders and some of its adherents from the Campbellite movement. However, by accepting the Book of Mormon, as well as the Doctrine and Covenants and the Pearl of Great Price as authoritative, along with the Bible, Mormonism abandoned the sola Scriptura doctrine of the Reformation. In incorporating these additional Scriptures, Mormonism, unlike Campbellism, departed from the pale of Christian orthodoxy by rejecting the Trinity, as defined in the early Church, deny the crucial need for faith in Christ as the only means of escaping damnation, and believe that the Substitutionary Atonement is not in itself sufficient payment for the sins of an individual. Mormonism departs from Protestantism, again unlike Campbellism, insofar as it rejects sola gratia, sola Scriptura, and sola fide.

Seventh Day Adventism and the Jehovah's Witnesses, which are an offshoot of the Adventists, have their roots in the Millerite movement. There are some similarities with Mormonism, insofar as both movements originated in upstate New York and both believed in an incomplete atonement and character perfectionism. Additionally, Adventism had its own variety of authoritative writings apart from the Bible: the visions of Ellen White. In this respect, this movement has a common ground with the Christian Science movement, which regards the works of Mary Baker Eddy as authoritative. Nonetheless, I don't believe the Adventists hold Ellen White's writings as on a par with Scripture, but believe them to be authoritative, not unlike Summa Theological is for Catholics.

However, the Millerite movement was largely a spinoff from the Baptist churches with a focus on the anticipated Second Coming of Christ in 1844 and had no particular association with Campbellism. Additionally, the mainstream of Adventism has gradually come closer to Christian orthodoxy and the Protestant "solas" in the last century. Mormonism has retained its distinctives.

If you mean Aquinas’ work, Summa Theologica is not authoritative; I would have used as examples of authoritativeness the ecumenical councils and infallible proclamations.

What Aquinas did was set to answer the major theological questions which might challenge the Christian (Catholic) church; in some cases his answers, such as the location of Eden, are speculative.

In fairness to Aquinas, his statements are often less speculative or inane as they are often said to be by Protestant satirists. For instance, such satirists often accuse Aquinas as debating how many angels could dance on the head of a pin. Actually, there is no such issue in Summa Theologica. The issue was actually whether angels have a physical form, that is, do they take up even the smallest amount of space; If it had been expressed in such an absured way, the actual “space” in question wasn’t the head of a pin, but the point of a needle. The actual issue is quite a source of significant contest to this day even among Protestant sects which ridicule the question. (I’ve seen the Mormon doctrine of the corporeality of spiritual beings a major source of scorn on FR, even.)