Anyone know where I can get textbooks, or at least portions, in a PDF online? (for free)

I’m still waiting for one of my textbooks to arrive in the mail and unfortunately have homework due in the class on Tuesday. I’m just wondering if anyone in the fluthersphere knows a good site to search for textbooks online or anything like that. I know it’s a stretch but I’m sweatin’ the small stuff waiting for my textbook to arrive. Any suggestions would be awesome.