Kumar, Mahesh, Sindhu M, M Sethumadhavan, and Lakshmy K V. “Distributed Human Interaction Proof for Public Blockchain Platform”. International Journal of Engineering and Technology 7, no. 3.34 (September 1, 2018): 885–889. Accessed August 17, 2025. https://mail.sciencepubco.com/index.php/IJET/article/view/19582.