Additional information about the slaughter of Christians in the Nigerian jihad can be found in these two recent publications:
UK All-Party Parliamentary Group, headed by Baroness Caroline Cox, released a report (June 2020). Here is a link to the .pdf: https://appgfreedomofreligionorbelief.org/media/200615-Nigeria-Unfolding-Genocide-Report-of-the-APPG-for-FoRB.pdf

Family Research Council released a report in early July. This link is to the press release, which provides a link to the .pdf:
https://www.prnewswire.com/news-releases/frc-releases-new-publication-showing-extent-of-christian-persecution-in-nigeria-301094406.html