Claudia L. Gray, Samantha L. L. Hill, Tim Newbold, Lawrence N. Hudson, Luca Börger, Sara Contu, Andrew J. Hoskins, Simon Ferrier, Andy Purvis & Jörn P. W. Scharlemann, 2016, Local biodiversity is higher inside than outside terrestrial protected areas worldwide, Nature Communications, 7, 12306, http://www.nature.com/ncomms/2016/160728/ncomms12306/full/ncomms12306.html