http://www.unodc.org/documents/human-trafficking/Migrant-Smuggling/Issue-Papers/Issue_Paper_-_A_short_introduction_to_migrant_smuggling.pdf
http://www.unodc.org/documents/human-trafficking/Migrant-Smuggling/Issue-Papers/Issue_Paper_-_A_short_introduction_to_migrant_smuggling.pdf