@article{singer1979ea,
  title={{Equality for Animals}},
  author={Singer, P.},
  journal={(1998) Environmental Ethics.(2nd) McGraw-Hill},
  pages={359--365},
  year={1979}
}

@book{kant1991mlg,
  title={{The Moral Law: Groundwork of the Metaphysics of Morals}},
  author={Kant, I. and Paton, H.J.},
  pages={57},
  year={1991},
  publisher={Routledge}
}