* [http://www.access.gpo.gov/uscode/title26/subtitlea_chapter1_subchapterf_parti_.html Internal Revenue Code] — Direct link to sections 501 through 505 at the [http://www.gpo.gov/ Government Printing Office]
* [http://www.allexperts.com/el/2266-9/Nonprofit-Law/ Ask Federal questions About Nonprofits in the United States - no cost]
* [http://www.data360.org/graph_group.aspx?Graph_Group_Id=267 Historical data regarding the number of 501(c) organizations in the U.S.]
* [http://www.irs.gov/pub/irs-pdf/p557.pdf IRS Publication 557], which governs 501(c) organizations
[[Kategori:Organisasi nirlaba yang berbasis di Amerika Serikat]]