At upper left, more toning. Plus, he's using the eraser to define the light direction, which seems to be behind her, to the right. Upper right, he's smudged the drawing again, and is nailing down tonations, hair and dress definately darker than skin. Also, changes to hair. Lower left, again smudged with more controlled eraser-work. Lower right, smudged again, relined in places, more controlled smoother gradations over all.