@misc{Aptroot2021,
  author    = {Andr{\´e} Aptroot},
  title     = {World key to the species of Pyrenulaceae and Trypetheliaceae},
  booktitle = {Archive for lichenology ; 29},
  issn      = {1868-4173},
  series    = {Archive for lichenology},
  number    = {29},
  type      = {workingpaper},
  pages     = {91},
  year        = {2021},
}