Title from PDF file caption (viewed Sept. 26, 2008).
Mode of access: Internet at the FAA web site. Address as of 9/26/08: http://www.airweb.faa.gov/Regulatory%5Fand%5FGuidance%5FLibrary/rgAdvisoryCircular.nsf/0/ceba7446f88ecfa1862569c3004ba827/$FILE/ATTZVBXH/ac20-41a.pdf; current access available via PURL.