1. Position of the American Dietetic Association on Vegetarian Diets
A translation of a huge article on vegetarianism and veganism. As the title suggests, the source is authoritative, and there are a ton of links to scientific papers. Obviously, the site itself is vegan, and therefore needs to be treated with a grain of salt, but if they haven't lied or omitted anything anywhere, it's pretty impressive.
The takeaways?