References missing in Monogame.Extended portable library

When I try to build my project, I get hundreds of unresolved references. Cannot add reference to a portable library. Get this message “All of the framework assemblies are already referenced.” How do I resolved all these references?
Thanks

By the way I am using Vs2017 with Nuget Manager

Need a little more info. What version of visual studio are you using? Windows? Etc?

Thanks for the reply. This works on VS2015 Windows 10.

Why do I get 800+ error messages when I try to install Monogame.Extended?

CS0234 The type or namespace name ‘Xna’ does not exist in the namespace ‘Microsoft’ (are you missing an assembly reference?) MonoGame.Extended C:\Users\lione\OneDrive\Documents\Visual Studio 2017\Projects\ParaformGame\MonoGame.Extended\Angle.cs 31 Active

How did you create your project to start with? Did you install the latest version of MonoGame and use one of the project templates? If so which one?