York, Denise and John (November 9, 2006). "Letter to 49ers Faithful". San Francisco 49ers. Archived from the original on September 28, 2007. Retrieved January 1, 2007.
Upton, John (January 31, 2013). "The San Francisco Retreat". Slate. Retrieved January 28, 2020. ...the roots of the team's southern migration can be traced back more than 15 years.
York, Denise and John (November 9, 2006). "Letter to 49ers Faithful". San Francisco 49ers. Archived from the original on September 28, 2007. Retrieved January 1, 2007.