Alfagi, A. S., A. Abd. Manaf, B. A. Hamida, and M. G. Hamza. “A Systematic Literature Review on Necessity, Challenges, Applications and Attacks of Watermarking Relational Database”. Journal of Telecommunication, Electronic and Computer Engineering (JTEC), vol. 9, no. 1-3, Mar. 2017, pp. 101-8, https://jtec.utem.edu.my/jtec/article/view/1752.