Reference

M. Dobbertin, P. Mayer, T. Wohlgemut, E. Feldmeyer-Christe, Ulrich Graf, N. E. Zimmermann, A. Rigling (2005): The Decline of Pinus sylvestris L. Froests in the Swiss Rhone Valley - a Result of Drought Stress?. – Phyton, Annales Rei Botanicae, Horn – 45_4: 153 - 156.