Obrtel R., 1948: Příspěvek k poznání cizopasných a býložravých blanokřídlých, (Tenthredionoidea, parsitic Hymenoptera). 20 pp.
 
FEB 12102
Obrtel R., 1949: K otázce druhů rodu Pristomerus Curt. 5 pp. [HYM 2829] Folia entomologica 12: 102-106.
 
HYM 2830
Obrtel R., Šedivý J., 1960: Hemiteles dodecellae n. sp. (Hym., Ichn.), a new parasite of the pine budworm. 3 pp. [M44]
 
ASC 57143
Obrtel R., Šedivý J., 1960: Hemiteles dodecellae n. sp. (Hym., Ichn.), a new parasite of the pine budworm. 3 pp. [M44] [HYM 2830] Acta Societatis entomologicae Cechosloveniae 57: 143-145.
 
51684
Oehlke J., 1964: Übersicht und Bestimmungstabelle der palaearktischen Gattungen der ehemaligen Unterfamilie Pimplinae auct. (Hymenoptera, Ichneumonidae). 58 pp. [M27]
 
HYM 2842
Ogloblin A. A., 1924: Description of new species and notes on some Anteoninae (Proctotrupidae) of Czechoslovakia. 15 pp. [M44]
 
ASC 22024
Ogloblin A. A., 1925: Descriptions of a new species of Pseudoisobrachium Kieff. (Hym. Bethylidae) from Brazil. 4 pp. [HYM 2845] Acta Societatis entomologicae Cechosloveniae 22: 24-27.
 
ASC 22077
Ogloblin A. A., 1925: Popisy tří nových druhů rodu Pseudoisobrachium Kieff. (Hym. Bethylidae) z Brazílie. 5 pp. [HYM 2846] Acta Societatis entomologicae Cechosloveniae 22: 77-81.
 
AEP 04145
Ogloblin A. A., 1926: A new species of Allotropa (Scelionidae, Hymenoptera). 6 pp. Acta Entomologica Musei Nationalis Pragae 4: 145-150.
 
AEP 05115
Ogloblin A. A., 1927: A new species of Loxotropa Foerst. (Hymen., Diapriidae) from Carpathian Russia in Czechoslovakia. 4 pp. Acta Entomologica Musei Nationalis Pragae 5: 115-117.
 
HYM 2867
Olmi M., 1975: Paradryinus afer sp. n. primo Driinide parassita degli Omotteri Fulgoroidei Ricaniidi del genere Ricania Germ. (Hymenoptera, Dryinidae). 6 pp.
 
SPX 21053
Olmi M., 1998: Taxonomic remarks on Australian Dryinidae with description of new species (Insecta, Hymenoptera, Chrysidoidea). 6 pp. Spixiana 21(1): 53-58.
 
SPX 27147
Olmi M., 2004: New species of Dryinidae from Colombia (Insecta, Hymenoptera, Chrysidoidea). 8 pp. Spixiana 27(2): 147-154.
 
SPX 28271
Olmi M., 2005: A contribution to the knowledge of Dryinidae of the Neotropical and Australian regions (Insecta, Hymenoptera, Chrysidoidea). 10 pp. Spixiana 28(3): 271-280.
 
SPX 31215
Olmi M., 2008: New species of Dryinidae from the Afrotropical Region (Insecta, Hymenotpera, Chrysidoidea). 7 pp. Spixiana 31(2): 215-221.
 
51701
Olmi M., Currado I., 1975: Su alcuni tipi di Dryinidae di Ljungh, Snellen van Vollenhoven a Klug (Bethyloidea). 20 pp.
 
HYM 2877
Ooststroom S. J. van, 1969: Over het voorkomen ven Pseudogonalos hahni (Spin.) in Nederland (Hym., Trigonal.). 4 pp.
 
EFA 1428
Ortiz-Sánchez F. J., 1993: Evaluation of the efficiency of Beehere ® as a honey bee (Apis mellifera Linnaeus, 1758) attractant to marrow crop (Cucurbita pepo Linnaeus, 1753) cultivated in greenhouse conditions in southern Spain. (Hymenoptera, Apidae). 7 pp. Entomofauna 14/28.
 
EFA 1818
Ortiz-Sánchez F. J., 1997: An update on the Ibero-balearic species of Xylocopa Latreille, 1802, with new data in Morocco (Hymenoptera, Anthophoridae). 8 pp. Entomofauna 18/18: 237-244.
 
SCZ 011
Osborn D. J., Krombein K. V., 1969: Habitats, flora, mammals, and wasps of Gebel’Uweinat, Libyan desert. 18 pp. Smithsonian Contributions to Zoology
 
EFA 0826
Osten T., 1987: Ein neuer Fundort von Proscolia spectator Day, 1981 (Hymenoptera, Aculeata). 8 pp. Entomofauna 8/26.
 
EFA 1127
Osten T., 1990: Beitrag zur Kenntnis der Scoliidenfauna von Zypern (Hymenoptera, Scoliidae). 9 pp. [M23] Entomofauna 11/27: 469-477.
 
EFA 1543
Osten T., 1994: Zweiter Beitrag zur Kenntnis der Scoliidenfauna von Zypern (Hymenoptera, Scoliidae). 7 pp. Entomofauna 15/43: 501-508.
 
EFA 1831
Osten T., 1997: Zur Taxonomie von Scolia (Discolia) mongolina Nagy, 1970 und Scolia (Scolia) incana Nagy, 1970 (Hymenoptera, Scollidae). 8 pp. [M23] Entomofauna 18/31: 513-520.
 
51709
Oudemans J. T., : Trichiosoma lucorum L. eine biologische studie. 21 pp.
 
EFA 2410
Özbek H., Coruh S., Kolarov J., 2003: A contribution to the Ichneumonidae fauna of Turkey. Subfamily Ichneumoninae (Hymenoptera). 8 pp. [M23] Entomofauna 24/10: 157-164.