K. El Kehal, D. Ennagoura, K. El Fahssi, B. Bossoufi, M. El Far, and M. T. Bennani, “Data Sampling Frequency Effects on Risk-Adjusted Cryptocurrency Portfolio Construction”, Eng. Technol. Appl. Sci. Res., vol. 16, no. 2, pp. 34264–34269, Apr. 2026.