Social network analysis of obsidian artefacts and Māori interaction in northern Aotearoa New Zealand Ladefoged, Thegn N. ; Gemmell, Caleb ; McCoy, Mark ; Jorgensen, Alex ; Glover, Hayley ; Stevenson, Christopher ; O'Neale, Dion Abstract Publication: PLoS ONE Pub Date: March 2019 DOI: 10.1371/journal.pone.0212941 Bibcode: 2019PLoSO..1412941L