Fort Vaux: Battleground Europe
This is one of Pen & Sword's "Battleground Europe" series.
It is a 200 page book packed with mainly practical information about Fort Vaux throughout the battle for Verdun. There are a number of "appendices", describing things like locations of graves, battlefield sites and so on; as well as four "tours" which take the reader who chooses to use the instructions to locations which are important to this story.
For anyone interested in understanding Verdun, this book would be a good starting point.