Both of these websites offer access to free textbooks and course materials in English. Many of the textbooks are for the sciences and for math, but look around to see if you can find things that interest you. The second link (http://ocw.mit.edu) is created by MIT, the Massachusetts Institute of Technology. This institution is a world-class engineering school. It is very very prestigious, and you can be absolutely sure that the material on the website is of a high quality.