http://www.pnas.org/content/108/13/5419.abstract (Publisher version)
Perin, R., Berger, T. K., & Markram, H. (2011). A synaptic organizing principle for cortical neuronal groups. Proceedings of the National Academy of Sciences of the United States of America, 108, 5419-5424. doi:doi: 10.1073/pnas.1016051108.