Flag and State Encyclopedia – flags and banners from all over the world https://www.flaggenlexikon.de/flag-encyclopedia/index_dt.htm
The great, comprehensive and synoptical Flag and State Encyclopedia with ca. 3500 depictions of flags from all over the world, among them many historical flags and banners. The Plus: The ingenious semiotic Flag-Finder!
For that is the flag, after hoisting it up, to set back on half-mast or half-pole