For me, it was introductory quantum mechanics (QM) books, you can go with MIT online course from Barton Zwiebach and online course from BLIS (This is for Rust/C implementation of BLAS). If you fall in love with QM and go for more rigorous formulation of its mathematical structure, you can follow it up with An Introduction to Hilbert Space by N. Young, which was the book used in my next semester for Hilbert Space Course.
Hilbert Space is the mathematical framework to describe QM systems.
You might enjoy "Thirty-three Miniatures" (2010) by Jiřì Matoušek. It's a collection of short applications of Linear Algebra in geometry, combinatorics and CS.
