Nowacki, Luciana Cristina, et al. “Analgesic Effect of Hypericum Perforatum, Valeriana Officinalis and Piper Methysticum for Orofacial Pain”. Brazilian Journal of Oral Sciences, vol. 14, no. 1, Mar. 2015, pp. 60-65, https://periodicos.sbu.unicamp.br/ojs/index.php/bjos/article/view/8640847.