RT Article T1 Assessing the validity of online drug forums as a source for estimating demographic and temporal trends in drug use JF Journal of addiction medicine VO 10 IS 5 SP 324 OP 330 A1 Paul, Michael J. A1 Dredze, Mark A1 Vandrey, Ryan G. A1 Johnson, Matthew W. A1 Chisolm, Margaret S. A2 Dredze, Mark A2 Vandrey, Ryan G. A2 Johnson, Matthew W. A2 Chisolm, Margaret S. LA English YR 2016 UL https://krimdok.uni-tuebingen.de/Record/1912463199 DO 10.1097/ADM.0000000000000238