I used https://www.youtube.com/watch?v=Xkcosme9hyE&list=PLy4zsTUHwGJKByTn_qV76oTpEYGczqEb_&index=24 and https://www.youtube.com/watch?v=gE4XMwV3mo4&list=PLy4zsTUHwGJKByTn_qV76oTpEYGczqEb_&index=26
