<ref name="Wheeler_1908">{{cite journal |first1=W. M. |last1=Wheeler |year=1908 |title=The polymorphism of ants |url=https://antcat.org/documents/3436/10548.pdf |journal=Annals of the Entomological Society of America |publisher= |volume=1 |issue= |pages=39–69 |doi= }}</ref>