This is the portrait drawing book of Chinese artist 冉茂芹 (Mau-Kun Yin).
It's a 336-page paperback filled with mostly portraits of just heads, and a small selection of nude figure drawing. They are either drawn with charcoal or graphite. These beautiful portraits are actually just sketches but rendered with realism and form. Most of the subjects are Asians with really distinct features and head shapes.
This is not an instructional book although the author does give some tips in the introduction, written in Chinese and English.
You can contact Basheer Graphic Books to order the book.