Deep Inside Deep Underground Military Bases

Why is there almost nothing written on Deep Underground Military Bases (DUMBs)?  Why are they so secret?  What is going on in them?

To discuss this we have one of the few people who has researched them, Dr. Richard Sauder,  Richard is the author of "Underground Bases and Tunnels" and "Under water and underground Bases".  His web site is http://eventhorizonchronicle.blogspot.co.uk/ .  You can also go to http://www.whale.to/b/underground_h.html although it is not related to Dr. Sauder's work.