Passas, Nikos. Informal Value Transfer Systems, Terrorism and Money Laundering. Washington: National Institute of Justice, 2003. Accessed 2 July 2013. https://www.ncjrs.gov/pdffiles1/nij/grants/208301.pdf
This comprehensive report defines Hawala through explaining informal value transfer systems, and besides discussing the complex process of such practices, it goes on to talk about law enforcement challenges and international legal asymmetries that make such activities possible.
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