Philip Barker Webb: Histoire Naturelle des Îles Canaries. Band 3, Teil 2 Abschnitt 1, 1841, 202–203 (online).
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Richard Thomas Lowe: Florulae Salvagicae Tentamen or a list of plants collected in the Salvages or Salvage Islands. John van Voorst, London 1869, S. 12 (online).