If you speak French there is a new series out now on finches being written up
in French with great detail on a number of species including Siskin, Scarlet Rosefinch and other nice finches which if you follow the link you can learn more on these superb publications worth noting!
The author is an acknowledged authority on the fringillidae of the world
and each publication goes into great detail in accurate and lucid specialist
terms to give a highly accurate account of each species covered by title.
They are monographs like for example the superb book by accomplished Sparrow authority Denis Summers Smith on the House Sparrow but these publications are a French series intended for readers with an interest
in species like Scarlet Rosefinch across their range including comprehensive treatement on their ecology in particular refering to French articles by French
authorities on the species.
Bertram.E.B.BREE in sunny Jersey.
Best wishes from the sunny side of the International Channel.