Scripting using external software

i am trying to write my programs in MonoDevelop and so far everything works out, the only problem is i can't find the correct .dll for my using statement to get hands on the VRage.MyFixedPoint. VRageMath doesn't have it and VRage.Math doesn't exist, tried to find some API references but most are outdated.

Does anyone know which dll to include?

Thanks Mahtrok