M. Neupane, S. Sharma, P. Dahal, L. K. Devkota, and R. P. Dhakal, “Engine Performance and Emission Analysis of TiO2 Nanoparticle-Enhanced Waste Cooking Oil Biodiesel”, Himalayan J. Appl. Sci. Engin., vol. 6, no. 2, pp. 59–73, Jan. 2026.