Chapter 23

www.census.gov/ipc/www/idb/

www.prb.org/

www.techkiva.com/teachcensus/PopPyr.htm

math.bu.edu/DYSYS/applets/

staff.science.uva.nl/~alejan/dynamicstour.html

www.census.gov/ipc/www/idb

http://forio.com/simulate/simulation/pontifexconsult/how-much-oil-is-left/