@article{article99c1787f,
title   = {Approximate von Neumann entropy for directed graphs},
author = {Cheng, Ye and Wilson, Richard C. and Comin, César H. and Costa, Luciano da Fontoura and Hancock, Edwin R.},
year = {2014},
doi = {10.1103/PhysRevE.89.052804},
journal   = {Physical Review E}
}