Nigerian citizens have authored many influential works of post-colonial literature in the English language. Nigeria's best-known writers are Wole Soyinka, the first African Nobel Laureate in Literature, and Chinua Achebe, best known for the novel ''Things Fall Apart'' (1958) and his controversial critique of Joseph Conrad. Other Nigerian writers and poets who are well known internationally include John Pepper Clark, Ben Okri, Cyprian Ekwensi, Buchi Emecheta, Helon Habila, T. M. Aluko, Isaac Delano, Chimamanda Ngozi Adichie, Daniel O. Fagunwa, Femi Osofisan  and Ken Saro-Wiwa, who was executed in 1995 by the military regime. Critically acclaimed writers of a younger generation include Adaobi Tricia Nwaubani, Chris Abani, Sefi Atta, Helon Habila, Helen Oyeyemi, Nnedi Okorafor, Kachi A. Ozumba, Sarah Ladipo Manyika, and Chika Unigwe.