@conference{3419,
  author = {M. Lombardi and Judah Levine and Mauricio Lopez and F. Jiménez and J. Bernard and M. Gertsvolf and H. Sanchez and O. Fallas and L. Forero and Ricardo de Carvalho and M. Fittipaldi and R. Solis and F. Espejo},
  title = {International Comparisons of Network Time Protocol Servers},
  year = {2014},
  url = {http://tf.boulder.nist.gov/general/pdf/2757.pdf},
}