1. Allen E K, Allen O N 1950. The anatomy of nodular growths on roots of Tribulus cistoides L. Proc. Soil Soc. Am., 14, 179–183.
2. Athar M 1980. Investigations on non-leguminous nodule bearing families of angiosperms from Karachi area with particular reference to Zygophyllaceae. MPhil thesis. University of Karachi.
3. Athar M, Mahmood A 1972. Root nodules in some members of Zygophyllaceae growing at Karachi University Campus. Pak. J. Bot., 4, 209–210.
4. Athar M, Mahmood A 1981. Extension of Rhizobium host range to Zygophyllaceae. In: Gibson A H, Newton D E, eds. Current Perspectives in Nitrogen Fixation. Australian Academy of Sciences, Canberra, 481.
5. Athar M, Mahmood A 1985. Nodulation and nitrogen fixation by Tribulus terresiris under natural conditions. Pak. J. Agrie. Res., 6, 101–106.