What factors contribute to Human trafficking?

What factors contribute to Human trafficking? CathyZimmerman ,MazedaHossain ,CharlotteWatts (2011, July) Human trafficking and health: A conceptual model to inform policy, intervention and research. https://www.sciencedirect.com/science/article/abs/pii/S0277953611003169 Patrick Belser (2005,Marc01)Forced Labour and Human Trafficking: Estimating the Profits https://papers.ssrn.com/sol3/papers.cfm?abstract_id=1838403 2. Where are all the victims of Human Trafficking? Amy Farrell ,Jack McDevitt, Stephanie Fahy (2010,April 08) Understanding the determinants of official identification of human trafficking incidents https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1745-9133.2010.00621.x Sigmon, Jane Nady (2008,May 19) Combating Modern-Day Slavery: Issues in Identifying and Assisting Victims of Human Trafficking Worldwide https://www.tandfonline.com/doi/abs/10.1080/15564880801938508 https://www.psychologytoday.com/us/blog/modern-day-slavery/201611/how-us-citizens-become-human-trafficking-victims 3.How do you identify a trafficking victim? http://www.usccb.org/about/anti-trafficking-program/identifying-trafficking-victims.cfm Wendy L. Patrick, Ph.D (2018,Jan 13) Look Closer: How to Spot Human Trafficking Victims https://www.psychologytoday.com/us/blog/why-bad-looks-good/201801/look-closer-how-spot-human-trafficking-victims https://www.cnn.com/2018/03/05/world/anti-trafficking-organizations-around-the-world/index.html