wxRegEx Library
The wxWidgets source code cites these copyright holders in the wxRegEx (Regular Expressions) Library.
Copyright: (c) 2000 Karsten Ballueder <ballueder@gmx.net>
2001 Vadim Zeitlin <vadim@wxwidgets.org>
In addition, the wxRegEx Class Reference in the wxWidgets documentation presents the following information about copyright holders on the wxRegEx Library.
"It is built on top of either the system library (if it has support for POSIX regular expressions - which is the case of the most modern [Unix OS's]) or uses the built-in Henry Spencer's library. Henry Spencer would appreciate being given credit in the documentation of software which uses his library, but that is not a requirement."
"On platforms where a system library is available, the default is to use the built-in library for Unicode builds, and the system library otherwise."
Notes
1. In the quote above, the term "Unix OS's" was substituted for the term "Unices" for clarity.
2. The Henry Spencer copyright has potential application only on Windows operating systems.