eBook Help

We’ve made every book on our site available in PDF and two eBook (electronic book) formats, so that they are compatible with any computer or digital device. This page will explain the basics of PDFs and eBooks, and answer questions for those inexperienced with reading books on a screen.

Why eBooks?

eBooks vs. PDFs

PDFs are basically just electronic images or static pictures of text. While these are ideal for printing documents to be read on paper, they are less than ideal for reading books on a digital device. Advantages of eBooks over PDFs include:

  • fonts on eBooks are resizable for more comfortable reading
  • background and colors can be adjusted on eBooks to one’s personal preference
  • eBook reader apps automatically bookmark your last position
  • with eBooks, you can easily jump to and from footnotes with a click
  • eBooks are legible on all device sizes, including phones with very small screens

Which Format?


There are two standard formats for eBooks: MOBI and EPUB. MOBI is a file format created by Amazon for use with their Kindle devices and Kindle apps. EPUB is the format used by every other e-reader app. Both formats are excellent, but EPUB is generally recommended because it supports more modern features and sometimes results in a better reading experience.

If you’re not sure what to choose, start by trying an EPUB, it will most likely be what you need. If, however, you already read books on a Kindle device, or from the Kindle app on your phone, tablet, or computer — then you should use the MOBI file format. Or, if you’re planning to read on an Android phone you might be better off starting with a MOBI instead of an EPUB.

Choosing a Format:

  • using a Mac, iPhone or iPad? Choose EPUB.
  • Android, Kindle device, or Kindle app? Choose MOBI.
  • None of the above? Choose EPUB.

What App Should I Use?

Almost any free eBook reader app should handle our books without a problem. Here are some platform-specific recommendations:

Android Device

  • Amazon Kindle app
  • Aldiko Book Reader

Apple Device (Mac, iPhone, iPad)

  • Apple “Books” app (recommended)
  • Amazon Kindle app

Windows PC / Device

  • Amazon Kindle app
  • Kobo app
  • Nook app

Get more help

If you’re still confused, or having any sort of technical problem with our books, or have a suggestion how we could improve the help on this page, please contact us! We’d love to hear from you and we’ll do our best to make sure you’re able to download and enjoy the incredible books on this site in a way that works for you.