Recently I have been interested in mobile learning and teaching and reading relevant sources. I came across an online available edited book: Mobile Learning: A handbook for educators and trainers. There are 20 chapters focusing on different aspects of mobile learning and teaching.
British Council shares a number of downloadable books on its website. Books on professional development, ELT research and resource packs for teachers are available in pdf format to download. Here is the list of the books I suggest for reading. I will give brief information about each book. For more downloadable books please visit the British Council webpage.