Sources:
https://www.permaculture.co.uk/articles/essential-guide-hazel
http://www.ecoenchantments.co.uk/myogham_hazelpage.html
https://www.thespruceeats.com/why-are-hazelnuts-called-filberts-1808319
https://www.arborday.org/programs/hazelnuts/consortium/agriculture.cfm
https://www.ireland-information.com/irish-mythology/fionn-irish-legend.html
https://www.yourirish.com/folklore/aillen-mac-midgna-goblin
https://www.wildernessireland.com/blog/build-bridge-myths-legends-giants-causeway/
https://stairnaheireann.net/2016/03/17/the-legend-of-sadhbh/