I don’t think there’s a reference. I believe it’s based on Stan’s face, just flip this image horizontally.

@Tekahem you can mute the video by using the volume control on the bottom right :)

On peut parler français, pas de problème. On a second thought, never mind, I don't know how to critique in french. So your assignment... right now Heads are very solid, I see you're trying to vary jaw shapes, very nice. There are some problems: Second head: you wouldn't see the outer cheek from this angle. I fell that you extended too much the chin. Third Head: Pay attention to the shape of the jaw. From this angle you might start to see a little bottom plane or at least the corners of the jaw would be lower. The other heads I think you're exaggerating the bottom third and you're drawing too much front plane. I'ts possible having wide faces and longer chins. But try really getting a grasp on the classic measures or in the future you may find it difficult drawing women for example. Good work, keep drawing, Best Regards

Good construction on this extreme angle! These are hard. Looks like you do what I do and identify the tip of the nose and how it sits over that far side eye? I can't see the reference image but I imagine that is the exact placement of eye and tip of nose. So everything look good except for the nose angles. Give the nose and head tilt a quick recheck for the angles. These head angles are tough (at least for me) and great to practice.