Original manuscripts

[violinconcerto]

Hello!

My little research about the compositions for concertante violin goes on to the next step and I would like to find and buy original handwritten manuscripts of scores for that instrumentation. I am based in Germany and finding auction houses here is easy and I also noticed some online webshops for "old books" that include manuscripts. But I ask myself how I can find such auction houses for other countries, especially eastern Europe. Does anyone here can lead me to such online shops or auction houses?

Thanks and best,
Tobias