Can the Subaltern Speak?). Mention themes that these four novels share to talk about the subaltern and can the voiceless be heard.

Our research is about Postcolonial Feminism and we are using Gayatri Spivak as our theoretical framework (her article mainly: Can the Subaltern Speak?). Mention themes that these four novels share to talk about the subaltern and can the voiceless be heard. The four novels are the following:
Wide Sargasso Sea Jean Rhys
Jane Eyre Charlotte Brontyo
Foe J.M Coetzee
Julys People Nadine Gordimer