The superciliary prominences are well, but not excessively, developed, and are separated by a median depression in the region of the glabella.
"The Antiquity of Man"
Charles Lyell
Certain fixed and easily recognised bony landmarks-the glabella, the external occipital protuberance, the lateral angular process, and the root of the zygoma-are taken, and connected by lines, which are further subdivided-always being bisected.
"Manual of Surgery Volume Second: Extremities--Head--Neck. Sixth Edition."
Alexander Miles Alexis Thomson