1. Section 55, Road Traffic Regulation Act,1984
2. https://www.sfmta.com/blog/san-francisco-adopts-demand-responsive-pricing-program-make-parking-easier.
3. Is the curb 80% full or 20% empty? Assessing the impacts of San Francisco's parking pricing experiment;Millard-Ball;Transport Res Pol Pract,2014
4. https://appyway.com/portfolio/connected-payments/.
5. https://www.eafo.eu/countries/european-union/23640/infrastructure/electricity/compare.