More than $1 billion needed annually to secure Africa's protected areas with lions - Lindsey, P; Miller, J; Petracca, L; Coad, L; Dickman, A; Fitzgerald, K; Flyman, M; Funston, P; Henschel, P; Kasiki, S; Knights, K; Loveridge, A; et al. (Proceedings of the National Academy of Sciences, 2018)