Ugusman, A.; Zakaria, Z.; Hui, C. K.; Nordin, N. A. M. M. Piper Sarmentosum Increases Nitric Oxide Production in Oxidative Stress: A Study on Human Umbilical Vein Endothelial Cells . Clinics 2010, 65 (7), 709-714. https://doi.org/10.1590/S1807-59322010000700010.