http://www.greatlakesdragaway.com/correctionfactors.html (http://www.greatlakesdragaway.com/correctionfactors.html)
http://cochise.uia.net/pkelley2/eight-to-quarter.htm (http://cochise.uia.net/pkelley2/eight-to-quarter.htm)
http://www.greatlakesdragaway.com/index.php?page=analyzers (http://www.greatlakesdragaway.com/index.php?page=analyzers)