Question: is this a 2) strong advice, 1) weak advice 0) no advice?

Among opioids, morphine has been the gold standard for control of postoperative and chronic pain (Anghelescu, Oakes, & Popenhagen, 2006; Chou, Clark, & Helfand, 2003; Collins & Weisman, 2003; Quigley, 2005; Vascello & McQuillan, 2006; Zernikow et al., 2006). 
user
This is no advice
assistant