@Article{palla2007quantifying,
  author = {Palla, Gergely and Barabási, Albert-lászló and Vicsek, Tamás and Hungary, Budapest},
  title  = {Quantifying social group evolution},

  year   = {2007},
  number = {},
  url    = {http://130.203.133.150/viewdoc/summary?doi=10.1.1.119.7541},

  const  = {\ text}
}