Lesson
PDF ebooks can be great for learning all kinds of things. Often these are available for free downloads from many websites. A PDF is often a higher quality document than a normal file because of the amount of time and effort they take to make. Sometimes you need to provide an email address in exchange for the free file. If you find a good one, it can be quite valuable and useful. Of course it depends upon the quality of the content, but if you look around enough, you will certainly find some great information on many topics, not only English learning.
If you check out the link on this next article you'll find a link for the best Spoken English PDF series I've seen so far.