A review found that manifestos by extreme-right attackers, including Anders Breivik and Brenton Tarrant, remained fully accessible online despite efforts to remove them. The documents were described as ideological guides that can contain instructions for planning attacks, and were especially easy to find through Google searches. After Tarrant killed 51 people at two mosques in New Zealand in 2019 and livestreamed the attack on Facebook, New Zealand and European governments established the Christchurch Call to limit the spread of such material. Professor Matthew Feldman said the initiative had achieved some success. He also said Facebook had removed 1.5 million copies of the livestream within 24 hours.