I don't have a link handy. But you can find quite a lot of reputable sources if you google it. The one over at perfect health diet includes citations, I believe.
selenium iodine hashimotos - Google Search
You can also see it by reading the biochemistry behind the iodine transport in the thyroid. It depends upon an enzyme (?) which requires selenium on two of the steps as far as I remember, and sodium through the sodium-iodide symporter. Any mismatch here may leave anti-tpo in the thyroid instead of quickly degrading it as should be done in healthy thyroids.
That's why you'd ensure adequate selenium level before adding iodine... especially in the case of hashi's/graves.
There is also quite a few different articles published under the title "Iodine, The Next Vitamin D?" Those articles usually describe the connection between iodine and selenium.
If you look for posts by me in this thread I have posted one PDF a couple of times that has a flow chart over some of the interactions/requirements for successfully increasing iodine in regard to thyroid function.
Edit: I found the chart (and the article is there too)
Google Image Result for http://www.lmreview.com/images/sized/assets/images/article_images/Iodinechart_1-590x848.gif
I started on my own. Here in Norway there is very little knowledge about thyroid function and iodine/selenium.... I have one of the best doc's available here and he recommended selenium (since selenium has been shown to decrease antibodies in several studies). He also did a 24hour urine iodine excretion test, but I didn't show especially low on that one. I've read Dr. Brownstein's book on iodine and now know that such a test isn't very reliable… and the low-level in Norway is VERY low.
And I'd point out that I didn't ramp up, but started stright on quite a high dose... That after seeing this lecture by Dr. Brownstein.