Research for Combat Mission: Battle for Normandy can be categorized into a number of different headings.
General Historical Background
Scenario Design (Battles and Campaigns)
There are a number of resources online and in print to assist CM fans.
There are a number of good general histories online and in print.
Combat Mission: Battle for Normandy
- U.S. Army "Green Books" - are available online
Combat Mission: Battle for Normandy Commonwealth Forces
- Official History of the Canadian Army in the Second World War - is also available online