Reference

A. Christmann, Wilhelm M. Havranek, Gerhard Wieser (1999): Seasonal Variation of Abscisic Acid in Needles of Pinus cembra L. at the Alpine Timberline and Possible Relations to Frost Resistance and Water Status. – Phyton, Annales Rei Botanicae, Horn – 39_4: 23 - 30.