Waisse, S. and Tarcitano Filho, C. M. (2015) “Opium before morphine: the elusive quest for the active principle of drugs”, Circumscribere International Journal for the History of Science, 16, pp. 93–102. Available at: https://revistas.pucsp.br/index.php/circumhc/article/view/25685 (Accessed: 5 December 2025).