Billen, J. P. J. 1997b. Morphology and ultrastructure of the metatibial gland in the army ant Dorylus molestus (Hymenoptera, Formicidae). Belgian Journal of Zoology 127:159-166.

Billen, J. P. J. 1998. Exocrine glands in the legs of ants. [Abstract.]. P. 64 in: Schwarz, M. P.; Hogendoorn, K. (eds.) 1998. Social insects at the turn of the millennium. Proceedings of the XIII International Congress of IUSSI. Adelaide, Australia. 29 December 1998 - 3 January 1999. Adelaide: XIII Congress of IUSSI, 535 pp.

Billen, J. P. J. 2000. A novel exocrine gland in the antennal scape of the army ant Eciton burchelli. Belgian Journal of Zoology 130:159-160.

Billen, J. P. J. 2000. Femoral and tibial glands in the ant genus Strumigenys (Hymenoptera, Formicidae). Belgian Journal of Zoology 130:111-115.

Billen, J. P. J. 2000. Novel exocrine glands in the hindleg tarsi of the ant Nothomyrmecia macrops. Australian Journal of Zoology 48:661-667.

Billen, J. P. J. 2002. XIV International Congress of IUSSI. The Golden Jubilee Proceedings. 27 July - 3 August 2002, Hokkaido University, Sapporo, Japan. Sapporo: XIV International Congress of IUSSI, 233 pp.

Notes: Billen (ed.)

Billen, J. P. J. 2002. A novel epithelial intramandibular gland in the ant Pyramica membranifera (Hymenoptera, Formicidae). Belgian Journal of Zoology 132:175-176.

Billen, J. P. J. 2009. Occurrence and structural organization of the exocrine glands in the legs of ants. Arthropod Structure and Development 38:2-15. PDF

Billen, J. P. J. 2017. The metapleural gland of Aneuretus simoni (Formicidae, Aneuretinae). Asian Myrmecology 9:5 pp. e009005. 10.20362/am.009005 PDF

Billen, J. P. J. 2019. Diversidad y morfología de las glándulas exocrinas en las hormigas. Pp. 165-174 in: Fernández, F.; Guerrero, R. J.; Delsinne, T. (eds.) 2019d. Hormigas de Colombia. Bogotá: Universidad Nacional de Colombia, 1198 pp. PDF

Billen, J. P. J.; Al-Khalifa, M. S.; Rilva, R. R. 2017. Pretarsus structure in relation to climbing ability in the ants Brachyponera sennaarensis and Daceton armigerum. Saudi Journal of Biological Sciences 24:830-836. 10.1016/j.sjbs.2016.06.007 PDF

Billen, J. P. J.; Attygalle, A. B.; Morgan, E. D.; Ollett, D. G. 1987. The contents of the Dufour gland of the ant Pogonomyrmex occidentalis. Pp. 426-427 in: Eder, J.; Rembold, H. (eds.) 1987. Chemistry and biology of social insects. München: Verlag J. Peperny, xxxv + 757 pp.

Billen, J. P. J.; Bauweleers, E.; Hashim, R.; Ito, F. 2013. Survey of the exocrine system in Protanilla wallacei (Hymenoptera, Formicidae). Arthropod Structure and Development 42:173-183. PDF

Billen, J. P. J.; Boven, J. K. A. 1983. The chemical composition of the Dufour gland contents of workers of the ant Formica cunicularia. A test for recognition of the species. Annales de la Société Royale Zoologique de Belgique 113(suppl.1):283-289.

Billen, J. P. J.; Boven, J. K. A. 1987. The metapleural gland in Old World army ants: a morphological and ultrastructural description (Hymenoptera, Formicidae). Revue de Zoologie Africaine (Tervuren) 101:31-41.

Billen, J. P. J.; Brandão, C. R. F.; Paiva, R. V. S. 1995. Morphology and ultrastructure of the pygidial gland of the ant Dinoponera australis (Hymenoptera, Formicidae). Papeis Avulsos de Zoologia (São Paulo) 39 (9):209-216. PDF

Billen, J. P. J.; Evershed, R. P.; Attygalle, A. B.; Morgan, E. D.; Ollett, D. G. 1986. Contents of Dufour glands of workers of three species of Tetramorium (Hymenoptera: Formicidae). Journal of Chemical Ecology 12:669-685.

Billen, J. P. J.; Evershed, R. P.; Morgan, E. D. 1984. Morphological comparison of Dufour glands in workers of Acromyrmex octospinosus and Myrmica rubra. Entomologia Experimentalis et Applicata 35:205-207.

Billen, J. P. J.; Gotwald, W. H., Jr. 1988. The crenellate lining of the Dufour gland in the genus Aenictus: a new character for interpreting the phylogeny of Old World army ants (Hymenoptera, Formicidae, Dorylinae). Zoologica Scripta 17:293-295. PDF

Billen, J. P. J.; Grasso, D. A.; Mori, A.; Le Moli, F. 2001. Structural and functional changes of the Dufour gland in gynes of the amazon ant Polyergus rufescens (Hymenoptera, Formicidae). Zoomorphology (Berlin) 121:55-61.

Billen, J. P. J.; Jackson, B. D.; Morgan, E. D. 1988a. Secretion of the Dufour gland of the ant Nothomyrmecia macrops (Hymenoptera: Formicidae). Experientia (Basel) 44:715-719.

Billen, J. P. J.; Jackson, B. D.; Morgan, E. D. 1988b. The contents of the pygidial gland of the primitive ant Nothomyrmecia macrops (Hymenoptera: Formicidae). Experientia (Basel) 44:794-797.

Billen, J. P. J.; Kerkhofs, H. L. P. 1985. Ultrastructure of the ovarioles in Formica ants (Hymenoptera, Formicidae). Mitteilungen der Deutschen Gesellschaft für Allgemeine und Angewandte Entomologie 4:332-334.

Billen, J. P. J.; Peeters, C. 1991. Fine structure of the gemma gland in the ant Diacamma australe (Hymenoptera, Formicidae). Belgian Journal of Zoology 121:203-210.

Billen, J. P. J.; Peusens, G. 1984. Ultrastructure de la glande propharyngienne chez les fourmis Formicines (Hymenoptera, Formicidae). Actes des Colloques Insectes Sociaux 1:121-129.

Billen, J. P. J.; Schoeters, E. 1994. Morphology and ultrastructure of the mandibular gland in Formica L. ants (Hymenoptera, Formicidae). Memorabilia Zoologica 48:9-16.

Billen, J. P. J.; Taylor, R. W. 1993. Notes on the aberant venom gland morphology of some Australian dolichoderine and myrmicine ants (Hymenoptera, Formicidae). Belgian Journal of Zoology 123:159-163.

Billen, J. P. J.; Vanelderen, N.; Ito, F. 2022. Survey of the exocrine glands in workers of the ant Leptanilla clypeata. Insectes Sociaux -:1-13. 10.1007/s00040-022-00861 PDF

Billen, J.; Gobin, B.; Ito, F. 1999. Fine structure of the postpygidial gland in Aenictus army ants. Acta Zoologica (Stockholm) 80:307-310.

Billen, J.; Ito, F. 2018. Novel thoracic glands in the ant Myopias hollandi. Arthropod Structure and Development 47:229-237. 10.1016/j.asd.2018.04.005 PDF