Quote from the book "Королева Ойкумены"

Suitable for smartphones, Android tablets, e-readers (except Kindle) and many programs

You can read the book directly in the browser

Accessible from nearly any device

Works on any computer

Works on any computer

Opens in Adobe Reader

Optimized and suitable for smartphones

Suitable for Android apps

Suitable for iOS devices (iPhone, iPad, iMac) and most reading apps