@book{Leinster2004,
  title={Higher operads, higher categories},
  author={Leinster, Tom},
  number={298},
  year={2004},
  publisher={Cambridge University Press}
}

@article{Leinster2001,
  title={Structures in higher-dimensional category theory},
  author={Leinster, Tom},
  journal={arXiv preprint math/0109021},
  year={2001}
}