You are downloading the MathRef XAP file v188.8.131.52 for Windows Phone. MathRef is a free and useful Productivity app: This app gives you just a sample over 1,400 helpful formulas, figures, tips, and examples. Math Ref is just an awesomely useful app for ... You can now download the offline XAP file to install & try it.
Download Locations for MathRef 184.108.40.206 XAP file
Important Notice: Now Due To Unspecified Limitations, You Can Not Use The Offline XAP 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 MathRef XAP file, move the file to your phone's SD card and then tap 'Install local apps' in the phone's App list.