Tolong jelaskan mengenai Catatan dari Kaisar Norton

Cowan, Robert Ernest. "Norton I, Emperor of the United States and Protector of Mexico (Joshua A. Norton, 1819-1880)" in Quarterly of the California Historical Society. San Francisco: California Historical Society, October 1923.

Cowan, Robert E., et al. The Forgotten Characters of Old San Francisco. Los Angeles: The Ward Ritchie Press, 1964.