Saskia Sassen works in the fields of globalization, international migration and urban studies. She is the author of more than ten books, the most well-known being The Global City: New York, London, Tokyo, which was first published in 1991 and republished ten years later as a new edition. In her research, Sassen posits the concept of an economy based on the concept of a global city: the contemporary global economy can be conceived of as a network of trade and finance chains whose links are composed of large (global) cities.