"African Writers Series (AWS) is a series of books by African writers that has been published by Heinemann since 1962. The series has ensured an international voice to major African writers—including Chinua Achebe, Ngũgĩ wa Thiong'o, Steve Biko, Ama Ata Aidoo, Nadine Gordimer, Buchi Emecheta, and Okot p'Bitek. The emphasis is on Anglophone Africa, although a number of volumes were translated into English from French, Portuguese, Zulu, Swahili, Acholi, Sesotho, Afrikaans, Luganda and Arabic."
TL&DR, the combination of folks choosing to leave out works from their lists that aren't already in the site directory, thinking "international" is two or three continents, and assuming that the only classics that have ever come out of Africa are "Things Fall Apart" and maybe "Cry, the Beloved Country" make for a nasty situation. I used the original AWS covers when I could find them, as I'm not interested in feeding into the worship of far more mainstream publishers.