Keywords: Christaller model 3.svg Christaller's third model of distribution of cities on space according to the administrative principle Christaller_model_3 jpg 2010-02-10 01 30 UTC Christaller_model_3 jpg Laotseuphilo derivative work Wgabrie <span class signature-talk >talk</span> SVG version Christaller_model_3 jpg Central place theory |