Billen, J. P. J. 1982a. The Dufour gland closing apparatus in Formica sanguinea Latreille (Hymenoptera, Formicidae). Zoomorphology (Berlin) 99:235-244.

Billen, J. P. J. 1982b. Ultrastructure of the Dufour gland in ants (Hymenoptera, Formicidae). [Abstract.]. P. 329 in: Breed, M. D.; Michener, C. D.; Evans, H. E. (eds.) 1982. The biology of social insects. Proceedings of the Ninth Congress of the IUSSI, Boulder, Colorado, August 1982. Boulder: Westview Press, xii + 420 pp.

Billen, J. P. J. 1984a. Morphology of the tibial gland in the ant Crematogaster scutellaris. Naturwissenschaften 71:324-325.

Billen, J. P. J. 1984b. Dufour gland morphology in ants (Hymenoptera, Formicidae). [Abstract.]. P. 503 in: XVII International Congress of Entomology 1984. Abstract Volume. Hamburg, Federal Republic of Germany, August 20-26, 1984. Hamburg: XVII International Congress of Entomology, 960 pp.

Billen, J. P. J. 1985a. Ultrastructure of the worker ovarioles in Formica ants (Hymenoptera: Formicidae). International Journal of Insect Morphology and Embryology 14:21-32.

Billen, J. P. J. 1985b. Comparative ultrastructure of the poison and Dufour glands in Old and New World army ants (Hymenoptera, Formicidae). Actes des Colloques Insectes Sociaux 2:17-26.

Billen, J. P. J. 1985c. Ultrastructure de la glande de Pavan chez Dolichoderus quadripunctatus (L.) (Hymenoptera, Formicidae). Actes des Colloques Insectes Sociaux 2:87-95.

Billen, J. P. J. 1986a. Morphology and ultrastructure of the Dufour's and venom gland in the ant, Myrmica rubra (L.) (Hymenoptera: Formicidae). International Journal of Insect Morphology and Embryology 15:13-25.

Billen, J. P. J. 1986b. Comparative morphology and ultrastructure of the Dufour gland in ants (Hymenoptera: Formicidae). Entomologia Generalis 11:165-181.

Billen, J. P. J. 1987a ("1986"). Morphology and ultrastructure of the abdominal glands in dolichoderine ants (Hymenoptera, Formicidae). Insectes Sociaux 33:278-295.

Billen, J. P. J. 1987b. New structural aspects of the Dufour's and venom glands in social insects. Naturwissenschaften 74:340-341.

Billen, J. P. J. 1987c. Morphology and ultrastructure of the exocrine glands in social Hymenoptera. Pp. 81-84 in: Eder, J.; Rembold, H. (eds.) 1987. Chemistry and biology of social insects. München: Verlag J. Peperny, xxxv + 757 pp.

Billen, J. P. J. 1988. Comparaison entre les fourmis australiennes des genres Myrmecia et Nothomyrmecia. Actes des Colloques Insectes Sociaux 4:27-33. PDF

Billen, J. P. J. 1989. Morphology of the cloacal gland in the ant Cataglyphis savignyi. Actes des Colloques Insectes Sociaux 5:301-306. PDF

Billen, J. P. J. 1990a. Phylogenetic aspects of exocrine gland development in the Formicidae. Pp. 317-318 in: Veeresh, G. K.; Mallik, B.; Viraktamath, C. A. (eds.) 1990. Social insects and the environment. Proceedings of the 11th International Congress of IUSSI, 1990. New Delhi: Oxford & IBH Publishing Co., xxxi + 765 pp.

Billen, J. P. J. 1990b. Morphology and ultrastructure of the Dufour's and venom gland in the ant Myrmecia gulosa (Fabr.) (Hymenoptera: Formicidae). Australian Journal of Zoology 38:305-315.

Billen, J. P. J. 1990c. The sting bulb gland in Myrmecia and Nothomyrmecia (Hymenoptera: Formicidae): a new exocrine gland in ants. International Journal of Insect Morphology and Embryology 19:133-139.

Billen, J. P. J. 1990d. A survey of the glandular systems of fire ants. Pp. 85-94 in: Vander Meer, R. K.; Jaffe, K.; Cedeno, A. (eds.) 1990. Applied myrmecology: a world perspective. Boulder: Westview Press, xv + 741 pp.

Billen, J. P. J. 1991. Ultrastructural organization of the exocrine glands in ants. Ethology Ecology and Evolution Special Issue 1:67-73.

Billen, J. P. J. (ed.) 1992. Biology and evolution of social insects. Leuven: Leuven University Press, ix + 390 pp.

Billen, J. P. J. 1992. Origin of the trail pheromone in Ecitoninae: a behavioural and morphological examination. Pp. 203-209 in: Billen, J. P. J. (ed.) 1992. Biology and evolution of social insects. Leuven: Leuven University Press, ix + 390 pp.

Billen, J. P. J. 1993. Morphology of the exocrine system in ants. Materialy Kollokviumov Sektsii Obshchestvennykh Nasekomykh Vsesoyuznogo Entomologicheskogo Obshchestva 2:1-15.

Billen, J. P. J. 1994a. Morphology and classification of the exocrine glands in ants. Ari 18:1-4.

Billen, J. P. J. 1994b. Morphology of exocrine glands in social insects: an up-date 100 years after Ch. Janet. P. 214 in: Lenoir, A.; Arnold, G.; Lepage, M. (eds.) 1994. Les insectes sociaux. 12ème congrès de l'Union Internationale pour l'Étude des Insectes Sociaux. Paris, Sorbonne, 21-27 août 1994. Paris: Université Paris Nord, xxiv + 583 pp.

Billen, J. P. J. 1997a. In memoriam. Jozef K.A. van Boven (1915-1997). Belgian Journal of Zoology 127:105-106.

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.