Steding-Jessen, Klaus, et al. “Using Low-Interaction Honeypots to Study the Abuse of Open Proxies to Send Spam”. INFOCOMP Journal of Computer Science, vol. 7, no. 1, Mar. 2008, pp. 44-52, https://infocomp.dcc.ufla.br/index.php/infocomp/article/view/205.