Chapter 5 – Culture and Society
Roett, Riordan & Sacks, Richard Scott (1991). Paraguay: The Personalist Legacy (pp.85-92). Westview Press: San Francisco.
   
Rubin – Bilingual Usage in Paraguay
Rubin, Joan (1968). Bilingual Usage in Paraguay. In Fishman (Ed.), Readings in the Sociology of language, pp.513-531. Paris: The Hague.

Section 2.3 – Diglossia and Bilingualism – from Romaine
Romaine, Suzanne (1995). Bilingualism (2nd Edition), pp.30-38. Blackwell Publishers: Malden, MA.
   
Diglossia – A. Hudson
Hudson, A (1997). Diglossia. In Spolsky (Ed.), Concise encyclopedia of educational linguistics, pp. 37-42. Amsterdam: Elsevier

http://www.arts.uwa.edu.au/LingWWW/LIN101-102/NOTES-102/Socio6.html

http://ccat.sas.upenn.edu/~haroldfs/messeas/diglossia/