Marcus, since I already asked in this forum about one particular plane - an Arado Ar-196 A-3 preserved in Bulgaria, I must correct your list of countries with planes. For some more information, please visit this sites:
http://hometown.aol.co.uk/balkandave/Plovdivair.html
http://www.abvg.net/Aircraft_Museum/
http://airforce.hit.bg/
http://www.geocities.com/bulgarian_a...on/English.htm
In general there is a very good, but a bit old book about many aviation museums in Europe in German language: "Luftfahrtmuseen Europa" by Rudolf Storck, Transpress Verlag, Berlin 1993, ISBN 3-344-70761-2.
(The Bulgarian museum from above is not included.)