Yifan Hu, Efficient and high quality force-directed graph drawing. The Mathematica Journal, 10 (37-71), 2005. 

@article{Hu_2005,
  author =      "Yifan Hu",
  title =       {Efficient and High Quality Force-Directed Graph Drawing},
  journal =     "Mathematica Journal",
  volume =      "10",
  year =        "2005",
  pages =       "37-71",
}


Tim Davis and Yifan Hu, The University of Florida Sparse Matrix Collection, ACM Transaction on Mathematical Software, 38 (1-25), 2011.

@ARTICLE{Davis_Hu_ufl_2009,
journal         = {{ACM} Transaction on Mathematical Software},
title           = {{University of Florida Sparse Matrix Collection}},
author          = {T. A. Davis and Y. Hu},
year            = {2011},
pages = {1-18},
volume =       "38",
note = {\url{http://www.cise.ufl.edu/research/sparse/matrices/}}
}