Go to the following URLs and enter GBSCS2ET as a redemption code to download the corresponding bonus pack:
Industrial (http://www.simcity.com/industrial)
Cyberpunk (http://www.simcity.com/cyberpunk)
European (http://www.simcity.com/european)
Smalltown (http://www.simcity.com/smalltown)
Authoritarian (http://www.simcity.com/authoritarian)