Koolnapadol, N., S. Sripattanapipat, and S. Skullong. “Effect of Pitch Spring of Delta-Winglets on Thermal Characteristics in a Heat Exchanger Tube”. Journal of Research and Applications in Mechanical Engineering 4, no. 2 (August 7, 2018): 166–174. Accessed December 5, 2022. https://ph01.tci-thaijo.org/index.php/jrame/article/view/138646.