PDF - http://papers.ssrn.com/sol3/Delivery.cfm/SSRN_ID788644_code114994.pdf?abstractid=695122&mirid=3
Eric Neumayer
"Nation-states employ visa restrictions to manage the complex trade-off between facilitating the entrance to their territory by passport holders from certain countries for economic and political reasons and deterring individuals from other countries for reasons of perceived security and immigration-control. The resulting system is one of highly unequal access to foreign spaces, reinforcing existing inequalities. Trans-national mobility is encouraged for passport holders from privileged nations, particularly rich Western countries, at the expense of severe restrictions for others. Visa restrictions manifest states' unfaltering willingness to monitor, regulate and control entrance to their territory in a globalised world. "
