Added one more firm in the lmAMM eventstudy example.

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/eventstudies@309 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Improved citation information.

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/eventstudies@310 edb9625f-4e0d-4859-8d74-9fd3b1da38cb