Links
[1] https://www.dmlp.org/resources/related-resources-prohibitions-political-and-legislative-activities
[2] https://www.dmlp.org/legal-guide/prohibitions-political-and-legislative-activities
[3] http://www.independentsector.org/programs/gr/lobbyguide.html
[4] http://www.nonprofitlawblog.com/home/2006/07/introduction_to.html
[5] http://www.pgdc.com/pgdc/article/2000/11/introduction-lobbying-charities
[6] http://www.abanet.org/buslaw/blt/2009-03-04/mehta.shtml
[7] http://www.nonprofitlawblog.com/home/advocacy_and_lobbying/page/2/