Yong Kim, Hae, and Joceli Mayer. “Data Hiding for Printed Binary Documents Robust to Print-Scan, Photocopy and Geometric Attacks”. Journal of Communication and Information Systems 23, no. 1 (June 18, 2015). Accessed May 25, 2020. https://jcis.sbrt.org.br/jcis/article/view/273.