The Anatomy Series: The Human Skull Reference Collection (Digital Download) contains 21 high-resolution images of the Human Skull (81MB PDF) to use as artist reference material to draw or paint from. 
 
When employed as artistic reference and re-interpreted into a new artistic work(s), the images come without copyright restriction and can be used personally and professionally. However, reproduction or replication of any direct image and sold or used is strictly prohibited. The direct images may not be republished, sold or distributed in any format or media.