1. Arosa ML (2008) Fern feeding ecology of the Azores bullfinch, Pyrrhula murina. MSc thesis. Universidade de Coimbra
2. Arosa ML, Quintanilla LG, Ramos JA, Ceia R, Sampaio H (2009a) Spore maturation and release of two evergreen Macaronesian ferns, Culcita macrocarpa and Woodwardia radicans, along an altitudinal gradient. Am Fern J 99:260–272
3. Arosa ML, Ramos JA, Valkenburg T, Ceia R, Laborda H, Quintanilla LG, Heleno R (2009b) Fern feeding ecology of the Azores bullfinch (Pyrrhula murina): the selection of fern species and the influence of nutricional composition in fern choice. Ardeola 56:71–84
4. BirdLife International (2008) Pyrrhula murina. In: IUCN (2008) 2008 Red list of threatened species. http://www.iucnredlist.org . Accessed 20 Feb 2010
5. Bowles ML, Whelan CJ (1994) Restoration of endangered species. Cambridge University Press, Cambridge