@article{SipmanAptroot1992,
  author    = {Harrie J. M. Sipman and Andr{\´e} Aptroot},
  title     = {Results of a botanical expedition to Mount Roraima, Guyana : 2., Lichens},
  journal   = {Tropical bryology},
  number    = {5},
  pages     = {79 -- 107},
  year      = {1992},
}