1. Integrated Taxonomic Information System (ITIS): http://www.itis. gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value= 29057
2. The plantlist: http://www.theplantlist.org/tpl/search?q=tribulus +terrestris
3. Tela Botamica: http://www.tela-botanica.org/page:eflore_bdtfx? type_nom=nom_scientifique&nom=tribulus&niveau=2&module=recherche&referentiel=bdtfx&action=rechercheSimple&submit=OK
4. Frohne D, Pfander HJ, Anton R (2009) Plantes à risques. Tec & Doc/EMinter, Paris
5. Wikimedia: https://commons.wikimedia.org/wiki/File:Tribulus_- terrestris_(Puncture_Vine_or_Gokharu)_in_Hyderabad_W_IMG_8892.jpg