Below is a short collection of introductory material which the faculty volunteers provided. Please note that this list is not actively maintained, was thrown together quickly in a distributed effort, and likely omits many excellent sources.
Handbook of Computational Social Choice Suggested from an author: "For voting theory, I think particularly relevant to EC are chapters 2 (voting theory), 6 (manipulation), 8 (rationalizations), 9 (combinatorial domains), 10 (preference elicitation) -- the other parts of the book are very relevant too though!"
Textbook Chapters on Approximation in Mechanism Design