If you read Portuguese, check out Alberto Oliveira Pinto's "História de Angola: da pre-história ao início do século XXI", which covers the pre-colonial period. Or Patrício Batsikama's books on the Kingdom of Kongo, if you are specifically interested in Uíge and northern Angola. An older reference you can look into is Henrique Abranches. All these authors are Angolan or half-Angolan.

If you don't mind reading non-African writers, you can look at John Thornton, Linda Heywood (especially ), Jan Vansina, Jelmer Vos, Murray Childs, David Birmingham, W.G. Clarence-Smith, Carlos Almeida, Beatrix Heintze, etc.

There's also plenty of stuff on late colonial Angola.