There is a small $7 booklet "Women Wartime Spies" in Barnes & Nobles. Very well written. Besides WWI, It also covers WWII. Old movie "Carve Her Name with Pride" was actually based real person's real story.
Book:
http://www.amazon.com/Women-Wartime-.../dp/B00FP14IKC
Movie:
http://en.wikipedia.org/wiki/Carve_Her_Name_with_Pride