Smith, Whitney, The Flag Book of the United States — The
Story of the Stars and Stripes and the Flags of the Fifty States,
rev. ed., New York, William Morrow & Co., Inc., 1975
For more in-depth material, there are also a few books on the flags
of a single state, such as Cannon, The Flags of Tennessee
[can90], and there are even books such
as Sumrall, Battle Flags of Texans in the Confederacy
[smr94]. There are also articles, such
as the history of the most recent change to the flag of Nevada that was
published in the 1994 copy of Raven
[fer94].