"Keep going," Mateo said, packing up his bag. "That PDF is the 'Integral Calculus' bible for a reason. Asin wrote it for the student who is tired of memorizing and ready to understand. But don't just read it. Do the problems. They build on each other. It’s an integral in itself."
If you have access to the text, here is how to get the most out of it: ricardo asin integral calculus pdf