Krumpal, Ivar, Ben Jann, Martin Korndörfer, and Stefan Schmukle. “Item Sum Double-List Technique: An Enhanced Design for Asking Quantitative Sensitive Questions”. Survey Research Methods 12, no. 2 (August 13, 2018): 91-102. Accessed June 22, 2021. https://ojs.ub.uni-konstanz.de/srm/article/view/7247.