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3. CBS Centraal Bureau voor de Statistiek (2014). Gemeenten verwachten 660 miljoen euro aan parkeerbelasting in 2014. https://www.cbs.nl/nl-nl/nieuws/2014/11/gemeenten-verwachten-660-miljoen-euro-aan-parkeerbelasting-in-2014.
4. NPR National Public Radio (2015). Map: The Most Common* Job In Every State. https://www.npr.org/sections/money/2015/02/05/382664837/map-the-most-common-job-in-every-state.