http://www.bbc.co.uk/news/magazine-16761784 How do you measure them? BBC The worlds biggest cities: How do you measure them? http://www.bbc.co.uk/news/magazine-16761784 do you measure Professor Kam Wing Chan The world's biggest cities: How do you measure them? BBC comparare le mele con le pere Professor Kam Wing Chan How do you measure them? BBC do you measure How do you measure them? The world’s biggest cities – how do we measure them? http://www.bbc.co.uk/news/magazine-16761784