Today I got hold of a book on the 109 in Finnish service titled MERSU. It is a rather expensive, and contains only Finnish words - no english summary or captions.
My finnish is not at all good - in fact it is non-existing, but being a 109aholic I had to have the book. From what I can see, it is a lot of information on the men that flew the machines, but with large photos of the men - and the machines!
There is however such a lot of pictures that it is reccomendable to anyone who wants some background for the colors of a finnish 109 for a build. Perhaps some online translation of the captions will be helpful, I have not tried it yet.
Anyway - it is expensive, and in a language most would not understand, and that should deter most people from buying it, but if in need of anything 109, it is a must.
I bought mine at my local bookstore, that got it from Finland. That way I probably paid a bit more than I could if buying it online, but I like to have local specialist stores - all the hobbyshops with plastic kits in my area are gone, and if I can help the old bookstore to keep going then I am OK with paying a little extra.
The cover;
Title: Mersu Messerschmitt Bf 109G Suomen ilmavoimissa
Author: Kari Stenman
ISBN-13: 978-952-229-188-2
Fomat: Hardcover
Pages: 400 pages
Dimensions: 310 x 237
Language: Finnish
Released: 2017
Publisher: Koala-Kustannus