A few references:
Baldauf Jr, R.B. and Ingram, D.E. (2003). Language-in-education planning. In W. Frawley (Ed.), International Encyclopedia of Linguistics (vol. 2) (2nd edn), 412-16. Oxford: Oxford University Press.
Cooper, Robert L., Shohamy, Elana, & Walters, Joel (Eds.). (2000). New perspectives in educational language policy: In honour of Bernard Dov Spolsky. Amsterdam & Philadelphia: John Benjamins Publishing Company. ?
Kaplan, R.B. (2005) Is language-in-education policy possible. In D. Cunningham and A. Hatoss (Eds). An International Perspective on Language Policies, Practices and Proficiencies. Melbourne: Australian Federation of Modern Language Teachers Association.
Liddicoat, A. (2013). Language-in-education Policies: The Discursive Construction of Intercultural Relations. Bristol: Multilingual Matters.
McGroarty, M. (2002). 2. Evolving influences on educational language policies. In J. W. Tollefson (Ed.), Language policies in education (pp. 17-36). Mahwah, NJ: Lawrence Erlbaum.
Spolsky, Bernard. (2008). Investigating language education policy. In K. A. King & N. H. Hornberger (Eds.), Encyclopedia of language and education, (Second ed., Vol. 10: Research methods in language and education, pp. 27-40). New York: Springer Science.
Tollefson, J. (2002). Language Policies in Education. Mahweh, NJ: Lawrence Erlbaum Associates.