Reference

Pan American Health Organization - Basic country health profile summary, general situation and trends for Puerto Rico.
http://www.paho.org/English/SHA/prflpur.htm

Constitution of the Commonwealth of Puerto Rico - We, the people of Puerto Rico, in order to organize ourselves politically on a fully democratic basis, to promote the general welfare, and to secure for ourselves and our posterity the complete enjoyment of human rights,...
http://welcome.topuertorico.org/constitu.shtml

U.S. Census Bureau - Estimates of the population of Puerto Rican Municipios: July 1, 1999, and demographic components of population change: April 1, 1990 to July 1, 1999.
http://www.census.gov/population/estimates/puerto-rico/prmunnet.txt

Economy at a Glance - The data displayed in this page is assembled from different surveys and programs conducted by the Bureau of Labor Statistics.
http://stats.bls.gov/eag/eag.pr.htm

Puerto Rico Census of Agriculture - Percent of farms and of cuerdas by value of sales, selected crops harvested, market value of crops sold, livestock, fish, poultry, and their products, and additional agricultural data from 1993 to 1998.
http://www.nass.usda.gov/census/census97/puertorico/puerto.htm

Languages Spoken in Puerto Rico - Ethnologue. Brief summary of the statistics of languages spoken.
http://www.sil.org/ethnologue/countries/Puer.html

Puerto Rico Fact Sheet - Country analysis brief by the United States Energy Information Administration.
http://www.eia.doe.gov/emeu/cabs/prico.html

The World Factbook - Profile of Puerto Rico by the Central Intelligence Agency (CIA).
https://www.cia.gov/library/publications/the-world-factbook/geos/rq.html