RT Article T1 Estimated drug use based on direct questioning and open-ended questions: Responses in the 2006 National Survey on Drug Use and Health A1 Kroutil, Larry A. A2 Colliver, James D. A2 Aldworth, Jeremy A2 Vorburger, Michael LA English YR 2010 UL https://krimdok.uni-tuebingen.de/Record/1912540126 NO 1557-0657 DO 10.1002/mpr.302