Reference

Ralf Kätzel, S. Löffler, H. Landmesser, Ch. Ringel, R. Hahn, Otto Wienhaus (2005): Needle Contents of Scots pine (pinus sylvestris L.) and Norway spruce (Pices abies (L.) Karst.) as Biomarkers for Assessment of Vitality in Comparison with the Crown Condition. – Phyton, Annales Rei Botanicae, Horn – 45_3: 117 - 137.