There is a early recording of Andrew Ng Stanford course before he became the star of the field. It is mostly math behind ML. There are also his lecture notes

There is a early recording of Andrew Ng Stanford course before he became the star of the field. It is mostly math behind ML. There are also his lecture notes from 2014 I suppose. It is really all one need to know. Machine learning or Deep learning is just pattern recognition which uses NNs as the basis for representation foe the "matcher". The real problem of ML is to find someone who would pay you for this because we are in a bubble. It is math and algorithms that matters and there are just a few of them. All the tooling could be mastered in a month.