Buters, JT;Kasche, A;Weichenmeier, I;Schober, W;Klaus, S;Traidl-Hoffmann, C;Menzel, A;Huss-Marp, J;Kramer, U;Behrendt, H.Year-to-year variation in release of Bet v 1 allergen from birch pollen: evidence for geographical differences between West and South Germany..Int Arch Allergy Immunol.2008.145.2.122-30