Breitbonde, L. B. (1991). “City, Countryside, and Kru Ethnicity”. Africa. 61 (2): 186–201. doi:10.2307/1160614. JSTOR1160614.
glottolog.org
Nordhoff, Sebastian; Hammarström, Harald; Forkel, Robert; Haspelmath, Martin biên tập (2013). “Kru”. Glottolog. Leipzig: Max Planck Institute for Evolutionary Anthropology.
Nordhoff, Sebastian; Hammarström, Harald; Forkel, Robert; Haspelmath, Martin biên tập (2013). “Siamou”. Glottolog. Leipzig: Max Planck Institute for Evolutionary Anthropology.
jstor.org
Breitbonde, L. B. (1991). “City, Countryside, and Kru Ethnicity”. Africa. 61 (2): 186–201. doi:10.2307/1160614. JSTOR1160614.