Budiman, G., A. B. . Suksmono, and D. . Danudirdjo. “FFT-Based Data Hiding on Audio in LWT-Domain Using Spread Spectrum Technique”. Elektronika Ir Elektrotechnika, vol. 26, no. 3, June 2020, pp. 20-27, doi:10.5755/j01.eie.26.3.23950.