Lecture 9: https://www.youtube.com/watch?v=cZS5of6cTOU&t=1550s
Lecture 10: https://www.youtube.com/watch?v=VZdSynFcO44&t=434s
Lecture 2: https://www.youtube.com/watch?v=fZ1mTIn3Ks0
Lecture 3: