In addition to the secondary sources on the home page of this guide, many organizations have put together material on school voucher systems. Good resources to familiarize yourself with the issues include:
School Vouchers are a controversal topic. When finding information about voucher systems online, be alert to the potential biases that organizations may have on the issue. Two organizations could portray the same data in very different lights. It is best to collect information from multiple sources when possible.
For additional information about a non-profit group, you can examine tax forms it files with the IRS at http://foundationcenter.org/findfunders/990finder/.