Azure Pipelines .net core 3.1 library with references to other libraries create one nuget package

I have Visual Studio solution with 10 .net core 3.1 library projects (let's call them CORE). One of them is a main project. It has references to other projects.

I want to have one nuget package (stored in azure feed) which I can use in my other solutions because I won't add all dlls every time when I need CORE functionality. I need to define Azure Pipeline to do that job. How to define that pipeline which produce one package containing all other references?