A. Hariyadi, M. A. Swasono, and A. C. Augusty, “Combination of Dragon Fruit, Hibiscus and Bitterleaf as Dye Sensitizer to Increase Efficiency of DSSC”, Int. J. Adv. Sci. Eng. Inf. Technol., vol. 7, no. 3, pp. 936–942, Jun. 2017.