This video from The Survival Podcast explains how to find free eBooks and cool documents online. As an example, he Googles "permaculture" looking for PDF files. He suggests adding "filetype:PDF" to his search. By doing this, he finds more extensive information, including a 155 page document about permaculture. A PDF file is something that can be downloaded and used on a Kindle to read later. He demonstrates how to download the file to his computer. He demonstrates again by searching for "making mead filetype:PDF" and finds much more downloadable information than he would if he had just searched for "making mead". This is a useful tool for finding large downloadable files and eBooks.