Grundt, Hanne Hegre; Bakkebø, Kjersti (16. april 2019). Barlind og kristtorn (plakat). NIBIO.
woodlandtrust.org.uk
ati.woodlandtrust.org.uk
«Ancient trees: the UK's oldest trees». Besøkt 19. juli 2021. «The oldest yew in the UK is said to be the Fortingall yew in Perthshire. It’s estimated to be between 2,000 and 3,000 years old, although some believe it could be 5,000 years old.»