The original paper: M. Rosvall and C. T. Bergstrom, Maps of
information flow reveal community structure in complex networks, PNAS
105, 1118 (2008) 10.1073/pnas.0706851105, https://arxiv.org/abs/0707.0609
A more detailed paper: M. Rosvall, D. Axelsson, and C. T. Bergstrom, The map
equation, Eur. Phys. J. Special Topics 178, 13 (2009).
10.1140/epjst/e2010-01179-1, https://arxiv.org/abs/0906.1405.