References:
Edexcel, (2008). Support and Guidance: Topic 3, Unit 4. http://www.google.co.uk/url?sa=t&rct=j&q=how+do+superpowers+use+direct+control&source=web&cd=1&ved=0CDEQFjAA&url=http%3A%2F%2Fwww.edexcel.com%2Fmigrationdocuments%2FGCE%2520New%2520GCE%2FUnit%25203%2520Contested%2520Planet%2520Superpower%2520Geographies.ppt&ei=yaa7UKL4NMia1AX4lYGIAg&usg=AFQjCNGXbyGV2PFZD7bKQky31Ifju86khA. Date accessed: 30/11/12
Revision World (year unknown). Superpowers. http://revisionworld.co.uk/a2-level-level-revision/geography/global-challenges-and-issues-0/superpowers. Date accessed: 30/11/12
Edexcel, (2008). Support and Guidance: Topic 3, Unit 4. http://www.google.co.uk/url?sa=t&rct=j&q=how+do+superpowers+use+direct+control&source=web&cd=1&ved=0CDEQFjAA&url=http%3A%2F%2Fwww.edexcel.com%2Fmigrationdocuments%2FGCE%2520New%2520GCE%2FUnit%25203%2520Contested%2520Planet%2520Superpower%2520Geographies.ppt&ei=yaa7UKL4NMia1AX4lYGIAg&usg=AFQjCNGXbyGV2PFZD7bKQky31Ifju86khA. Date accessed: 30/11/12
Revision World (year unknown). Superpowers. http://revisionworld.co.uk/a2-level-level-revision/geography/global-challenges-and-issues-0/superpowers. Date accessed: 30/11/12