https://www.youtube.com/watch?v=2rncVW3mkhE
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3604862/
https://openbareonderzoeken.onroerenderfgoed.be/openbareonderzoeken/106/bijlagen/478
https://www.livescience.com/28082-medieval-monks-cultivated-wetlands.html
https://www.durfdenken.be/en/research-and-society/stonehenge-reveals-traces-much-older-past