USAGov for Nonprofits Contains information on grants, loans, management and operations, and tax information from the U.S. government for nonprofit organizations.
Foundation Center Comprehensive information on private, corporate, and community foundations; public charities; the fund-raising process; and writing grant proposals. Click on the link to Gain Knowledge to search their Catalog of Nonprofit Literature and locate their research studies.
Independent Sector Coalition of U. S. charitable and philanthropic foundations and corporate-giving organizations. Web site contains some free research publications, public policy statements, and accountability information for organizations and nonprofits.