Preparation for the rigors of an economics graduate programme I realize now that my undergraduate program is not nearly as rigorous as it should be - it required almost no math to complete. This is concerning because I've been accepted into a decent (top 30) PhD program. However, I (luckily) am also completing a degree in mathematics.

My question: 

Can anyone recommend a good textbook(s) to help me bridge the gap between my non-rigorous program and a PhD program (level of rigor is whatever might be typical of a top 30 school??). I would also love any online resources such as video lectures, problem sets with solutions etc.  

I looked at MIT's OCW but most of the courses beyond the principles do not include lectures, which was really disappointing.
I'd work my way through Microeconomic Analysis by Hal Varian (the PhD level one) and Mathematics for Economists by Simon and Bloom. You'll need both the micro intuition  of the former and mastery of the math bits of the the latter. You'll need thornier and more technical books at some point but these authors will hold your hand enough to work through them solo.