@article{poll1999algebra,
  title     = {Algebra of Programming by Richard Bird and Oege de Moor, Prentice Hall, 1996 (dated 1997).},
  author    = {Poll, Erik and Thompson, Simon},
  journal   = {Journal of Functional Programming},
  volume    = {9},
  number    = {3},
  pages     = {347--354},
  year      = {1999},
  publisher = {Cambridge University Press}
}

@book{adamek1990abstract,
  title     = {Abstract and concrete categories},
  author    = {Ad{\'a}mek, Ji{\v{r}}{\'\i} and Herrlich, Horst and Strecker, George},
  year      = {1990},
  publisher = {Wiley-Interscience}
}