Decided to change the titles on these deviations since they are technically not "tutorials" but just my own drawing studies.
For the head angles I used this
as reference. It's really handy I must say. One day I shall manage to draw the whole "map" on my own : >
At the moment I'm a bit too tired trying to dig out all the othe references I used on the other studies, I'll prob make a journal with links to them sooner or later.