You are downloading the Bookmobile AppX file v188.8.131.52 for Windows Phone. Bookmobile is a free and useful Books & Reference app: Web app for Scribd, Issuu, and Google ... You can now download the offline AppX file to install & try it.
Download Locations for Bookmobile 184.108.40.206 AppX file
Important Notice: Now Due To Unspecified Limitations, You Can Not Use The Offline AppX File To Install It Any More.
To try to install it manually from an SD card, you should choose one of the server location above to get the offline Bookmobile AppX file, move the file to your phone's SD card and then tap 'Install local apps' in the phone's App list.