OK...if you plug in "eternal marriage" to the search feature, you will come across a group of links. One of these is labeled, "Red Brick Store-Key Events".
Clicking on this link takes you to a group of scriptures. The last of the scriptures listed is D&C Section 132. If you click on the tab that is labeled "Readings", and then click on "Doctrinal Developments in Nauvoo", it will take you to the following .pdf file, which is part of a CES manual. If you scroll down to the section on plural marriage, it says the following:
The law of celestial marriage, as outlined in this revelation, also included
the principle of the plurality of wives. In 1831 as Joseph Smith labored on the
inspired translation of the holy scriptures, he asked the Lord how he justified
the practice of plural marriage among the Old Testament patriarchs. This
question resulted in the revelation on celestial marriage, which included an
answer to his question about the plural marriages of the patriarchs.11
First the Lord explained that for any covenant, including marriage, to be
valid in eternity it must meet three requirements (see D&C 132:7): (1) It
must be “made and entered into and sealed by the Holy Spirit of promise.”
(2) It must be performed by the proper priesthood authority. (3) It must be
by “revelation and commandment” through the Lord’s anointed prophet
(see also vv. 18–19). Using Abraham as an example, the Lord said he
“received all things, whatsoever he received, by revelation and
commandment, by my word” (v. 29). Consequently, the Lord asked, “Was
Abraham, therefore, under condemnation? Verily I say unto you, Nay; for I,
the Lord, commanded it” (v. 35).
Moreover, Joseph Smith and the Church were to accept the principle of
plural marriage as part of the restoration of all things (see v. 45).
Accustomed to conventional marriage patterns, the Prophet was at first
understandably reluctant to engage in this new practice. Due to a lack of
historical documentation, we do not know what his early attempts were to
comply with the commandment in Ohio. His first recorded plural marriage
in Nauvoo was to Louisa Beaman; it was performed by Bishop Joseph B.
Noble on 5 April 1841.12 During the next three years Joseph took additional
plural wives in accordance with the Lord’s commands.
As members of the Council of the Twelve Apostles returned from their
missions to the British Isles in 1841, Joseph Smith taught them one by one
the doctrine of plurality of wives, and each experienced some difficulty in
understanding and accepting this doctrine.13 Brigham Young, for example,
recounted his struggle: “I was not desirous of shrinking from any duty, nor
of failing in the least to do as I was commanded, but it was the first time in
my life that I had desired the grave, and I could hardly get over it for a long
time. And when I saw a funeral, I felt to envy the corpse its situation, and
to regret that I was not in the coffin.”14
After their initial hesitancy and frustration, Brigham Young and others
of the Twelve received individual confirmations from the Holy Spirit and
accepted the new doctrine of plural marriage. They knew that Joseph Smith
was a prophet of God in all things. At first the practice was kept secret and
was very limited. Rumors began to circulate about authorities of the Church
having additional wives, which greatly distorted the truth and contributed
to increased persecution from apostates and outsiders. Part of the difficulty,
of course, was the natural aversion Americans held against “polygamy.”
This new system appeared to threaten the strongly entrenched tradition of
monogamy and the solidarity of the family structure. Later, in Utah, the
Saints openly practiced “the principle,” but never without persecution.
This is the full reference link:
http://www.ldsces.org/inst_manuals/Chrc ... 000_23.pdf
So there you have it, folks!
BC was right about the references being there.
But I don't think the Church is just trying to openly broadcast the information. Otherwise, it wouldn't be so difficult to find. And, why aren't there any direct references on the site, itself? You would think that the plural marriages would be recorded clearly in the open on a site which includes the supposed history and lineage of Joseph Smith.