A burgher brief is a business licenses. Those records are also available at the St. Croix Landmarks Society Library at Estate Whim. Here is an article that can give you some info about the data base that makes it easy to locate information.

http://www.stjohnhistoricalsociety.org/Articles/AfricanRoots...

You may also Google African Roots Project to get updated information. That data base was launched in July 2009. It is also available at the Florence Williams Library in Christiansted.