<ref name="Ward_1988">{{cite journal |first1=P. S. |last1=Ward |year=1988 |title=Mesic elements in the western Nearctic ant fauna: taxonomic and biological notes on ''Amblyopone'', ''Proceratium'', and ''Smithistruma'' (Hymenoptera: Formicidae) |url=https://antcat.org/documents/3147/2954.pdf |journal=Journal of the Kansas Entomological Society |publisher= |volume=61 |issue= |pages=102–124 |doi= }}</ref>