C.  van Achterberg and Braet, Y., ?Two new species of Pambolus Haliday (Hymenoptera: Braconidae: Pambolinae) from Argentina?, Zoologische Mededelingen Leiden, vol. 78, no. 22, pp. 337-344, 2004.

G.  Simbolotti, Villemant, C., and van Achterberg, C., ?Notes on the genus Mama Belokobylskij (Hymenoptera: Braconidae: Euphorinae), and on the use of monotype taxa?, Zoologische Mededelingen, vol. 78, no. 1969, pp. 451-459, 2004.

X. - X.  Chen, Belokobylskij, S. A., van Achterberg, C., and Whitfield, J. B., ?Cornutorogas, a new genus with four new species of the subfamily Rogadinae (Hymenoptera: Braconidae) from the Oriental region?, Journal of Natural History, vol. 38, no. 17, pp. 2211-2223, 2004.

C.  van Achterberg and Berry, J., ?Neptihormius gen. nov.(Hymenoptera: Braconidae: Hormiinae), a parasitoid of Nepticulidae (Lepidoptera) from New Zealand?, Zoologische Mededelingen Leiden, vol. 78, no. 18, pp. 291-299, 2004.

C.  van Achterberg, ?Bitomoides gen. nov.(Hymenoptera: Braconidae: Opiinae) from Europe?, Zoologische Mededelingen Leiden, vol. 78, no. 21, pp. 331-335, 2004.