1. Amazon Mechanical Turk. https://mturk.com. Accessed May 2020
2. ClickWorker. https://www.clickworker.com. Accessed May 2020
3. Regulation (EU) 2019/2144 of the European Parliament and of the Council. https://eur-lex.europa.eu/eli/reg/2019/2144/oj. Accessed May 2020
4. South African Road Traffic Signs Manual. https://www.transport.gov.za/. Accessed June 2020
5. UpWork. https://www.upwork.com/. Accessed May 2020