Coleman, D. Potential Contributions and Challenges of VGI for Conventional Topographic Base-Mapping Programs // Crowdsourcing Geographic Knowledge: Volunteered Geographic Information (VGI) in Theory and Practice. New York, London: Springer Science+Business Media Dordrecht. 2013. 245–264. doi:10.1007/978-94-007-4587-2. ISBN978-94-007-4586-5.