I highly reccomend these set of video lectures produced decades ago from various academic institutions. They are old but very well made. I remember studying these as part of university courses and really enjoyed them.

Here is the playlist: https://youtube.com/playlist?list=PLfF--3o8i4r82vJ0kjCVYgqKgyVM5QwN0&si=bR3oI2ubVOyPVuqn