Sinchaisri, P. (1983) “Study on Pyrethrin Content in Pyrethrum Flower Head at Different Stages of Development ”, Thai Agricultural Research Journal, 1(1), pp. 31–34. available at: https://li01.tci-thaijo.org/index.php/thaiagriculturalresearch/article/view/245705 (accessed: 2 October 2026).