P. Utomo, N. Nasution, Arisman, R. Sembiring, "A Theoretical and Experimental Comparison of One Time Pad Cryptography using Key and Plaintext Insertion and Transposition (KPIT) and Key Coloumnar Transposition (KCT) Method", Advances in Science, Technology and Engineering Systems Journal, vol. 2, no. 5, pp. 31-34 (2017).