<ref name="Ward_1987">{{cite journal |first1=P. S. |last1=Ward |year=1987 |title=Distribution of the introduced Argentine ant (''Iridomyrmex humilis'') in natural habitats of the lower Sacramento Valley and its effects on the indigenous ant fauna |url=https://antcat.org/documents/3146/2953.pdf |journal=Hilgardia |publisher= |volume=55 |issue=2 |pages=1–16 |doi= }}</ref>