Recommendations for resources to read, to understand HLSL?

(I understand 3D math in general; but vague on shader math and syntax - I’ve made minor changes to existing shaders over several years, but that was all in XNA 3.1 for some old DX version. I never “mastered” that old shader version.)

I know about:

https://msdn.microsoft.com/en-us/library/windows/desktop/bb509638(v=vs.85).aspx

And I just found, but have not read yet:

http://www.neatware.com/lbstudio/web/hlsl.html
http://rbwhitaker.wikidot.com/hlsl-tutorials
http://www.catalinzima.com/xna/tutorials/crash-course-in-hlsl/
https://takinginitiative.wordpress.com/2011/01/12/directx10-tutorial-9-the-geometry-shader/
http://www.riemers.net/eng/Tutorials/DirectX/Csharp/Series3/HLSL_Introduction.php