Reference
Günther Zellnig, Manfred Karl Gailhofer, Hartwig Wilfried Pfeifhofer, Dieter Grill (1989): Ultrastructure and Pigment Composition of Chloroplasts of Differently Damaged Green and Yellow Needles of Picea abies. – Phyton, Annales Rei Botanicae, Horn – 29_2: 213 - 225.