V.  Antonova and Penev, L., ?Classification of Ant Assemblages (Hymenoptera: Formicidae) in Green Areas of Sofia?, Acta Zoologica Bulgarica, vol. 60, Suppl. 2, pp. 103-110, 2008.

V.  Antonova and Penev, L., ?Changes in the zoogeographical structure of ants (Hymenoptera: Formicidae) caused by urban pressure in the Sofia region (Bulgaria)?, Myrmecological News, vol. 8, pp. 271?276, 2006.