I have begun to make many of my diagrams available as eBooks.  I am selling them through the Amazon Kindle, the Apple iBooks store, and the Barnes and Noble store.  The Amazon Kindle store and Barnes and Noble store do not require you to have a ereader device, but you do need the free ereader software for your computer or device of choice that Amazon or Barnes and Noble provide.  Click on a title to go to the Publisher’s site and to find out where to purchase and see the contents of each ebook.