Google Play 图书
Google LLC
Box
Amazon Kindle
Amazon Mobile LLC
Audible – 亚马逊有声读物
Audible, Inc
Epic：儿童故事与教育读库
Epic! Creations Inc
Libby由OverDrive赛阅提供
OverDrive, Inc.
ThriftBooks: New & Used Books
Thrift Books Global, LLC.
Bookshelf
Vital Source Technologies
Barnes & Noble NOOK
Barnes & Noble
Goodreads
