Volume 2 is essential because it decodes the "confusing" systems of markings and colors that were often implemented inconsistently during the height of WWII.
Volume 2 dedicates entire plates to interior colors, documenting which variant was used by which manufacturer (Grumman vs. Vought vs. Douglas).
Websites will tell you a color "looks like" something. Monogram tells you the chemical formula and the official stock number. For museums restoring an FM-2 Wildcat or a T-6 Texan (used as a hacksaw in the late 40s), this guide is the signed affidavit of authenticity.
The book details the transition from high-visibility markings to the Blue-Grey over Light Gull Grey schemes adopted shortly after the attack on Pearl Harbor.
Across its 194 pages, the book breaks down technical aviation markings into specialized chapters: