Viascience explains by sourcing original paper from giants like Einstein, Bohr directly rather then give second-hand materials. What’s impressive is how lucid and clear the original author explained the most complicated idea from very beginning.

Secondly, it’s more from Doctorphys. He emphasizes importance of computing with real pen/pencile and derive all math yourself.

Below viascience’s explanation of angular momentum, spin need to be revisited.

And in referencing textbook This series draws from several sources, especially from the 1935 text by Pauling and Wilson, Introduction to Quantum Mechanics, reprinted by Dover Publications,1985, ISBN 978-0-486-64871-2; Cohen-Tannoudji, Diu and Laloe, Quantum Mechanics, Wiley, 1977, ISBN 0-471-16432-1; and I. N. Levine, Quantum Chemistry, 7th ed., Pearson, 2013, ISBN 978-0321803450.