@article{AmaralGoldbergerHavlinetal.1999,
  author    = {Luis A. Nunes Amaral and Ary L. Goldberger and Shlomo Havlin and Michael Rosenblum and Zbigniew R. Struzik and H. Eugene Stanley and Plamen Ch. Ivanov},
  title     = {Multifractality in human heartbeat dynamics},
  year      = {1999},
}