2014.08.21~2014.09.04
參考連結
http://blog.humblebundle.com/post/95926633860/more-perks-join-the-humble-bookperk-bundle
http://blog.humblebundle.com/post/95296282742/the-humble-bookperk-bundle-has-books-with-perks
http://us7.campaign-archive1.com/?u=a42731fd3353ff4c76f7f11bb&id=b6389dbbb4
http://us7.campaign-archive1.com/?u=a42731fd3353ff4c76f7f11bb&id=cd044fe043