Please find below some of the important links which I collated on Microsoft Core .NET Platform. Hope this information will be beneficial for your team.
.NET Framework Conceptual Overview
The .NET Framework has two main components: the common language runtime and the .NET Framework class library. The common language runtime is the foundation of the .NET Framework.
About Microsoft .NET 3.5 Framework
Microsoft .NET Framework version 3.5. Framework is an integral Windows component that supports building and running the next generation of applications and Web services. The key components of the .NET Framework are the common language runtime (CLR) and the .NET Framework class library, which includes ADO.NET, ASP.NET, Windows Forms, and Windows Presentation Foundation (WPF).
.NET Framework 3.5 Architecture
The architecture of the .NET Framework version 3.5 and 3.5 Service Pack 1 (SP1) builds upon the earlier versions of the .NET Framework.
.NET Framework System Requirements
.NET Framework Technologies
Tools and Utilities
Learning and Certification