S. Keharom, S. Techawongstien, R. Mahachai, and S. Chanthai, “Analysis of capsaicin and dihydrocapsaicin from sweet-to-very hot chilli peppers using an ultrasound-assisted extraction followed by RP-HPLC-PDA”, Asia Pac J Sci Technol, vol. 20, no. 1, pp. 54–65, Mar. 2015.