What is SDK
SDK is a set of tools that helps you to integrate functionalities into any application, including Web SDK, Mobile SDK, Visualization SDK, Web Services SDK, Office SDK, and Intelligence Server SDK.
Where to get documentations and resources
There are several websites you can get more information from, including MicroStrategy Community (https://community.microstrategy.com/), MicroStrategy Developer Zone (https://community.microstrategy.com/t5/custom/page/page-id/developer-zone), API reference, MicroStrategy discussion forums, and MicroStrategy knowledge base: