Lewis, S W.(2012). The potential for international and transnational public service advertising in public spaces in American and Chinese global cities: Conclusions from a 2010 survey of advertisements in subways in Beijing, New York, Shanghai and Washington, DC. Public Relations Review, 38(5), 765-778. doi:10.1016/j.pubrev.2011.10.007

Lewis, Steven W. "The Potential for International and Transnational Public Service Advertising in Public Spaces in American and Chinese Global Cities: Conclusions From a 2010 Survey of Advertisements in Subways in Beijing, New York, Shanghai and Washington, DC". Public Relations Review, 38.5 ( 2012 ): 765-778.