There are some great books on the Farquharson rifles. Wal Winfer's series on single shots includes an entire volume on George Gibbs Farquharsons and another on Jeffery and the trade Farquharsons.
Kirton's book on the "British Falling Block Rifle From 1865" is also a great book for anyone interested in Farquharson rifles.

As for the Farquharson name, or John Farquharson the inventor of the action, I don't know any books offhand other than those I mentioned.