Me pēnei te tohu i te whārangi:
Ants Roberts, 'Ngā whakaahua, ngā rauemi katoa', Te Ara - the Encyclopedia of New Zealand, http://www.TeAra.govt.nz/mi/fertiliser-industry/media (accessed 19 April 2024)
He kōrero nā Ants Roberts, i tāngia i te 24 Nov 2008