Dear Wruce Bayne,
Well, the first such quote would be directly from a publication which was approved and released under the signature of the First Presidency with the LDS Church logo on the back (which is basically the definition of an authoritative text in the Church):
Do not date until you are at least 16 years old. Dating before then can lead to immorality, limit the number of other young people you meet, and deprive you of experiences that will help you choose an eternal partner.
(For the Strength of Youth, Dating, 24)
So... that is pretty much the doctrine of the church. It is a statement endorsed by all of the 12 Apostles and First Presidency (I'm not sure where you're getting 13... that is a little odd).
But, if that is not good enough for you... let's go for direct quotes:
Gordon B. Hinckley:
"The Lord has made us attractive one to another for a great purpose. But this very attraction becomes as a powder keg unless it is kept under control. It is beautiful when handled in the right way. It is deadly if it gets out of hand.
"It is for this reason that the Church counsels against early dating. This rule is not designed to hurt you in any way. It is designed to help you, and it will do so if you will observe it.
"Steady dating at an early age leads so often to tragedy. Studies have shown that the longer a boy and girl date one another, the more likely they are to get into trouble.
"It is better, my friends, to date a variety of companions until you are ready to marry. Have a wonderful time, but stay away from familiarity. Keep your hands to yourself. It may not be easy, but it is possible."
("A Prophet's Counsel and Prayer for Youth," Liahona, April 2001, 38-39)
Boyd K. Packer:
Dating should not even begin until you are 16. And then, ideal dating is on a group basis. Stay in group activities; don't pair off. Avoid steady dating. Steady dating is courtship, and surely the beginning of courtship ought to be delayed until you have emerged from your teens."
("You're in the Driver's Seat," New Era, June 2004, 8.)
David B. Haight (former Apostle... maybe he was your 13th):
"Refrain from early dating or going steady. Avoid at all cost the familiarity trap. Instead of spending time in a lovers' lane, why not develop your minds and your personalities?" (Ensign, Nov. 1977, 58).
The policy of the church as laid out by the First Presidency is that we are not to date before we are 16. Dictionaries call a date "a romantic social engagement." So, don't sit around trying to convince yourself that all your time spent with that specially good looking "friend" isn't really dating.
Even after 16, we are encouraged to go on group dates until we are older and seriously looking for an eternal companion.
The policy and doctrine is pretty clear. If you're looking for excuses... for heaven's sake just WAIT. It isn't that long... and it won't seriously stunt your social development to wait a little longer to start dating. In fact, you will find that your maturity will make your relationships with members of the opposite sex to be much healthier. Of course, we can't guarantee
healthy relationships... that is up to you.
That is all.
Horatio the Love Doctor