A.  Kremer, Dupouey, J., Deans, J., Cottrell, J., Csaikl, U., Finkeldey, R., Espinel, S., Jensen, J., Kleinschmit, J., Van Dam, B., Ducousso, A., Forrest, I., U. de Heredia, L., Lowe, A., Tutkova, M., Munro, R., Steinhoff, S., and Badeau, V., ?Leaf morphological differentiation between Quercus robur and Quercus petraea is stable across western European mixed oak stands?, Annals of Forest Science, vol. 59, pp. 777-787, 2002.