More written for professionals, and be warned that the background and type used makes it very hard to read especially if you have a migraine. It does have a paragraph at the end that actually tells the migraineur how to take the magnesium.

I really liked this link. It is not for the beginner, but is really full of excellent information and on a page this specific I like to see a nice mix that includes good traceable medical research and articles. The rest of the site has other information about magnesium that might be worth checking out as well.