Human Male and Female Skulls: African, Asian, and European - Bone Clones, Inc. - Osteological Reproductions
Eye Drawing Tips - I love how quickly this escalates. It's like: well first ya got yer guidelines here, those'll help ya get started. Then yer gunna wanna sketch up a rough version of what yer goin fer AND THEN PERFECTION ONLY PERFECTION. But seriously helpful.