But be careful, there are many "download" links which aren't the actual book, they're advertisements. The real downloads are in the center of the page, in-between the book description and the place where it says "Sponsored High Speed Downloads".
 It has many textbooks and solution manuals. You have to upload one item for every item you download (unless you pay money). Try uploading any PDF or image you have on your computer. If you don't have one, download one from google images first.
 Feel free to add to this list.
Check ebookee.org.
Check scribd.com.
Try: http://www.hathitrust.org/ and http://www.freetechbooks.com/ .
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