Potency trends of Δ9-THC and other cannabinoids in confiscated cannabis preparations from 1993 to 2008 - Mehmedic, Z; Chandra, S; Slade, D; Denham, H; Foster, S; Patel, A S; Ross, S A; Khan, I A; ElSohly, M A (J Forensic Sci, 2010)