The core implementations for the DateTime.pm and DateTime::Duration
modules come from Date::ICal and Date::ICal::Duration, both of which
were written by Rich Bowen <rbowen@rcbowen.com> with help from the
Reefknot team.

Parts of the API come from Time::Piece, by Matt Sergeant
<matt@sergeant.org>, who had help from Jarkko Hietaniemi <jhi@iki.fi>.
That API was originally created by Larry Wall.

The DateTime::Language functionality is largely based on the
Date::Language modules that come with Graham Barr's <gbarr@pobox.com>
TimeDate module suite.  The strftime method in this module also
borrows heavily from Graham's implementation.

Matthew Simon Cavalleto implemented the week_{year,number}
functionality.
