<ref name="Billen_&_Boven_1987">{{cite journal |first1=J. P. J. |last1=Billen |first2=J. K. A. |last2=Boven |year=1987 |title=The metapleural gland in Old World army ants: a morphological and ultrastructural description (Hymenoptera, Formicidae) |url= |journal=Revue de Zoologie Africaine (Tervuren) |publisher= |volume=101 |issue= |pages=31–41 |doi= }}</ref>