In 2003, Ruben van Wendel de Joode, Hans de Bruijn, and Michel van Eeten published a paper entitled Protecting the Virtual Commons: Self-organizing Open Source Communities and Innovative Intellectual Property Regimes. The introduction of the paper begins by establishing that the open source and free software virtual communities of the internet are unique virtual communities; unlike others, they have been popular for a long time and have had significant economic impact. Further, the introduction contrasts open source and free software development to proprietary computer software development.