Greetings Colonial Wargamers!
Part of the challenge of doing a colonial war is finding good resources, especially in English, when the combatants are not English!!
I have listed nearly all the resources I can think of for the Tonkin Wars below. This includes histories, wikipedia, uniform information, etc.
Osprey's new French Naval & Colonial Troops 1872 - 1914: Great for uniforms and some history.
Foundry Books, which may no longer be in print. This is the Indo-China and Burma one:
War and Peace in Hanoi and Tonkin - By: Hocquard, Edouard from White Lotus Press
Wikipedia French version translated. This has more information than the English version when I last checked. Online translation is available. This is great for French Orders of battle.
The Tonkin Campaign of 1884 by James G. Scott (Nafzinger collection)
Nafzinger also has unit histories you can download for all the French Colonial troops.
Sino-French Naval War 1884-1885
EBooks
There are plenty of ebooks in English and French in archive.org. You may also have to weed out the US Gulf of Tonkin titles.
Photos, Drawings, and Sketches
Searching the web can yield some tremendous finds, but you should use both French and English spellings of the locations and units to get the images. Here are a couple I found.
Eric