Some books about the participating German countries in the French Revolution. Most of these fought in the 1792-1795 period as part of the Coalition armies. Colourful uniforms reminding of the Seven Years War. Starting with the Hanoverian army. Both books together gives a good overview of the army.
The Hessen were also part of the Armies of the Coalition.
The Mecklenburger were a kind of subsidy troops for the Dutch Republic. I have two books, one Dutch and one German about this small corps.
Of the Baden troops I have sadly only one of two books. Still searching for the second in which the infantry is described.