Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. People who wish to be identified as coming from Sheffield call themselves Sheffielders. The latest (2008 est.) population estimate for the City of Sheffield is 534,500 residents. This represents an increase of about 17,000 people since the last census in 2001.People from Sheffield are colloquially known to residents of the surrounding towns of Barnsley, Doncaster, Rotherham and Chesterfield as "dee-dars", which derives from the traditional pronunciation of the "th" in the dialectal words "thee" and "thou", still used, especially by older people, in South Yorkshire. Many Yorkshire dialect words and aspects of pronunciation derive from old Norse due to the Viking influence in this region.