A few references:
Batibo, H. M. (2009). Language documentation as a strategy for the empowerment of the minority languages of Africa. In I Selected proceedings of the 38th annual conference on African linguistics, red. av Masangu Matondo, Fiona Mc Laughlin & Eric Potsdam (pp. 193-203).
Bielenberg, B. (1999). Indigenous language codification: Cultural effects. Revitalizing indigenous languages, 103-112.
Francis, N. (1999). Bilingualism, writing, and metalinguistic awareness: Oral-literate interactions between first and second languages. Applied Psycholinguistics, 20(4), 533-561.
Frawley, W. J., Hill, K. C., & Munro, P. (Eds.). (2002). Making dictionaries: Preserving indigenous languages of the Americas. Univ of California Press.
Matras, Y. (1999). Writing Romani: the pragmatics of codification in a stateless language. Applied linguistics, 20(4), 481-502.
Milroy, J. (2001). Language ideologies and the consequences of standardization. Journal of sociolinguistics, 5(4), 530-555.
Ong, W. J., & Hartley, J. (2012). Orality and literacy: The technologizing of the word. (30th Anniversary Edition). New York: Routledge.
Vansina, J. (1965). Oral tradition. Transaction Books.
Vansina, J. M. (1985). Oral tradition as history. Univ of Wisconsin Press.