1. António de Oliveira de Cadornega, História Geral das Guerras Angolanas (Lisbon edition, 1940–2, 3 vols).
2. José Joaquim Lopes de Lima, Ensaios sôbre a Statistica das Possessões Portuguezas (Lisbon, 1846, vol. 3).
3. J. W. Blake, Europeans in West Africa (London 1942, 2 vols)
4. David Birmingham, ‘Central Africa from Cameroun to the Zambezi’, in Cambridge History of Africa, vol. 3 (1977).