“Determination of Phosphodiesterase Type 5 Enzyme (PDE-5) Inhibitors and Analogues As Adulterants in Selected Herbal Products Using Gas Chromatography–Electron Impact-Mass Spectrometer (GC-EI-MS)”. 2020. Baghdad Science Journal 17 (4): 1190. https://doi.org/10.21123/bsj.2020.17.4.1190.