Engelhardt, MD, PhD, FRCA, T., Zaarour, MD, C., & Crawford, MBBS, FRCPC, M. W. (2017). Plasma cyclic guanosine 3′,5′-monophosphate levels: A marker of glutamate-nitric oxide-guanyl cyclase activity?. Journal of Opioid Management, 7(6), 462–466. https://doi.org/10.5055/jom.2011.0087