1. Krombholz, K., Hobel, H., Huber, M., & Weippl, E. (2015). Advanced social engineering attacks. Journal of Information Security and Applications, 22, 113-122. In Section 1, Paragraph 1, the paper defines social engineering as attacks that "directly target the human user in order to retrieve sensitive information." DOI: https://doi.org/10.1016/j.jisa.2014.09.005
2. MIT OpenCourseWare. (2014). 6.858 Computer Systems Security, Fall 2014. Lecture 19: Web Security. Massachusetts Institute of Technology. The lecture notes define social engineering as an attack that "tricks a legitimate user into misusing their authority," which aligns with gaining confidential information through deception.
3. Mouton, F., Leenen, L., & Venter, H. S. (2016). Social Engineering Attack Detection Model: A Literature Review. In Information Security South Africa (ISSA), 2016 (pp. 1-8). IEEE. The paper's introduction (Section I) states, "Social engineering is the art of manipulating people into performing actions or divulging confidential information." DOI: https://doi.org/10.1109/ISSA.2016.7802920