How to learn the math behind machine learning and deep learning Models?

I am weak in machine learning and deep learning theory and background, or basically the math. I understand the Models as visualizations, but I want to understand the math. So, any reference you recommend to make me understand the maths?

I am good at math, so I want a reference or course to explain the maths concepts of the models not to explain the math as an intro to DL.

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