1. APG 1998. See general references.
2. APG II 2003. See general references.
3. Barker, R.J. 1996. New taxa, new combinations, keys and comments on generic concepts of Zygophyllum and a new species of Tribulus (Zygophyllaceae) in the manuscripts of the late H.J. Eichler. J. Adelaide Bot. Gard. 17:161–172.
4. Barker, R.J. 1998a. Notes on the genus Tribulopis (Zygophyllaceae) in Australia. J. Adelaide Bot. Gard. 18:77–93.
5. Barker, R.J. 1998b. A trial key and notes on Tribulus (Zygophyllaceae) in Australia, including one new species and validation of Tribulus suberosus. Nuytsia 12:9–35.