@article{KaldewaijS91,
  title={The derivation of a tighter bound for top-down skew heaps},
  author={Kaldewaij, A. and Schoenmakers, B.},
  journal={Information Processing Letters},
  volume={37},
  number={5},
  pages={265--271},
  year={1991},
  publisher={Elsevier}
}