Are you talking about bilingual as in using another language since childhood? Also, what is this speech for (ie. high school English class, undergrad speech class, your job...etc., etc.)?
I am not sure what library resources are available to you, so I will just give you a lot of resources and hopefully you find one of these available to you in your area.
Encyclopedia of Human Development. Ed. Neil J. Salkind. Vol. 1. Thousand Oaks, CA: Sage Reference, 2006. p168-170. (found using Gale Virtual Reference Library which is a database)
Lee, E., & Norton, B. (2009). The English language, multilingualism, and the politics of location. International Journal of Bilingual Education & Bilingualism, 12(3), 277-290. (Found on Academic Search Complete--it has a downloadable .pdf)
Hopefully this is helpful to you...
Hopefully this is the kind of stuff you're interested in...
Here is a link to census info. regarding language spoken at home other than english
http://factfinder.census.gov/servle...2008_3YR_G00_S1601&-ds_name=ACS_2008_3YR_G00_
factfinder.census.gov also has other information for people in the US that speak a language other than English.
If you are unsure of what reference material is available to you in your area, usually local libraries (public and university regardless of memberships or whatever) offer an "ask a librarian" feature. Also, you can PM me because I have access to pretty much every database imaginable through my university and I'm a librarian