Oberholser H. C., 1896: Descriptions of two new subspecies of the dowmy woodpecker, Dryobates pubescens (Linnaeus). 4 pp. 

 Oberholser H. C., 1899: A revision of the wrens of the genus Thryomanes Sclater. 30 pp. 

 Oberholser H. C., 1900: A list of the birds collected by Mr. R. P. Currie in Liberia. 14 pp. 

 Oberholser H. C., 1900: Catalogue of a collection of birds from Madagascar. 14 pp. 

 Oberholser H. C., 1900: Notes on birds collected by doctor W. L. Abbott in Central Asia. 24 pp. 

 Oberholser H. C., 1900: Notes on birds from the Cameroons district, West Africa. 9 pp. 

 Oberholser H. C., 1900: Notes on some birds from Santa Barbara Islands, California. 6 pp. 

 Oberholser H. C., 1902: Catalogue of a collection of hummingbirds from Ecuador and Colombia. 34 pp. 

 Oberholser H. C., 1903: List of birds collected by William T. Foster in Paraguay. 21 pp. 

 Oberholser H. C., 1903: Some new South American birds. 10 pp. 

 Oberholser H. C., 1904: A review of the wrens of the genus Troglodytes. 15 pp. 

 Oberholser H. C., 1904: A revision of the American great horned owls. 16 pp. 

 Oberholser H. C., 1904: Descriptions of a new african weaver-bird. 1 pp. 

 Oberholser H. C., 1906: Notes on birds from German and British East Africa. 11 pp. 

 Oberholser H. C., 1909: A revision of the kingfisher genus Ramphalcyon (Pelargopsis). 23 pp. 

 Oberholser H. C., 1911: A monograph of the flycatcher genera Hypothymis and Cyanonympha. 31 pp. 

 Oberholser H. C., 1911: A revision of the forms of the hairy woodpecker Dryobates villosus (Linnaeus). 28 pp. 

 Oberholser H. C., 1913: A revision of the forms of the great blue heron (Ardea herodias Linnaeus). 29 pp. 

 Oberholser H. C., 1914: A monograph of the genus Chordeiles Swaison, type of a new family of goatsuckers. 5 plates, 123 pp. 

 Oberholser H. C., 1915: A review of the subspecies of the ruddy kingfisher, Entomothera coromanda (Linnaeus). 19 pp. 

 Oberholser H. C., 1916: A synopsis of the races of the crested tern, Thalasseus bergii (Lichtenstein). 13 pp. 

 Oberholser H. C., 1916: Critical notes on the subspecies of the spotted owl, strix occidentalis (Xantus). 7 pp. 

 Oberholser H. C., 1917: The birds of Bawean Island, Java Sea. 16 pp. 

 Oberholser H. C., 1919: A review of the subspecies of the leach petrel, Oceanodroma leucorhoa (Vieillot). 8 pp. 

 Oberholser H. C., 1919: Birds collected by Dr. W. L. Abbott on various Islands in the Java Sea. 24 pp. 

 Oberholser H. C., 1920: A revision of the subspecies of the white-collared kingfisher, Sauropatis chloris (Boddaert). 45 pp. 

 Oberholser H. C., 1920: Notes on the wrens of the genus Nannus Billberg. 14 pp. 

 Oberholser H. C., 1920: The birds of the Tambelan Islands, South China Sea. 15 pp. 

 Oberholser H. C., 1920: The races of the Nicobar megapode, Megapodius nicobariensis Blyth. 4 pp. 

 Oberholser H. C., 1925: Notes on birds collected by Dr. W. L. Abbott on the Karimata Islands, off West Borneo. 4 pp. 

 Oberholser H. C., 1937: A revision of the clapper rails (Rallus longirostris Boddaert). 42 pp. 

 Obhlídal F., 1977: Ornitologická příručka. 302 pp. Druhé vydání 

 Obrhelová N., 1978: Die Gattung Umbra Walbaum (Pisces) im Nordböhmischen Tertiär Entwicklungsgeschichte der Esocoidei Berg im Lichte der Funktionalen analyse. 54 pp. Acta Musei Nationalis Pragae 34B(2-4): 119-172.

 Obrhelová N., 1985: Osteologie a ekologie dvou druhů rodu Prolebias sauvage (Pisces, Cyprinodontidae) v západočeském spodním miocénu. 64 pp. Acta Musei Nationalis Pragae 41B(1-2): 85-148.

 Obrhelová N., 1993: Ökologie der Fischassoziation im Miozänen Flözdach des Nordböhmischen Braunkohlenbeckens. 32 pp. Acta Musei Nationalis Pragae 49B(1-4): 111-142.

 Obrtel R., Holišová V., 1974: Trophic niches of Apodemus flavicollis and Clethrionomys glareolus in a lowland forest. 37 pp. Acta Scientiarum Naturalium Academiae Scientiarium Bohemoslovacae Brno (N.S.) 8(7): 1-37.

 Obuch J., 1994: Príspevok k pomernému zastúpeniu mikromammálií v Turci. 6 pp. 

 Occhipinti A., (ed.), 1995: Ecologia della Padania. Atti del XII convegno nazionale del gruppo per l’ecologia di base “G. Gadio”. Ferrara, Museo civico di storia naturale, 7-9 maggio 1994. 405 pp.  Sleva 50%!

 Occhipinti A., (ed.), 1995: Ecologia della Padania. Atti del XII convegno nazionale del gruppo per l’ecologia di base “G. Gadio”. Ferrara, Museo civico di storia naturale, 7-9 maggio 1994. 405 pp.  Sleva 20%!

 Odier F., Vago C., Lamy M. E., 1974: Persistence of virus of vertebrates in the hemocoel of insects: Study on the Poliovirus into the larvae of Coleoptera. 7 pp. (in French). [EVE 948] [COL 1664]  Annales de la Societe entomologique de France (N.S.) 10(2): 449-455.

 Ogilby J. D., 1911: Descriptions of new or insufficiently described fishes from Queensland waters. 24 pp. 

 Ohara M., 2010: Training courses for taxonomists and parataxonomists. 10 pp. (in Japanese). Japanese Journal of Entomology (N.S.) 13(2): 83-92.

 Ohba S.-Y., 2011: Field observation of predation on a turtle by a giant water bug. 2 pp. Entomological Science 14(3): 364-365.

 Oijen M. J. P. van, 2004: Haplochromis ushindi spec. nov., the largest piscivorous cichlid in the Mwanza Gulf area of Lake Victoria (East Africa) before the Nile perch upsurge. 6 pp. Zoologische Mededelingen Leiden 78: 249-255.

 Oijen M. J. P. van, Roselaar C. S., 2007: Notes on types and early specimens of Bombycivora japonica von Siebold, 1824, and of Bombycilla phoenicoptera Temminck, 1828. 8 pp. Zoologische Mededelingen Leiden 81: 251-258.

 Oijen M. J. P. van, Zeeuw M. P. de, 2008: Haplochromis vonlinnei spec. nov., a piscivorous haplochromine cichlid (Teleostei, Perciformes) from the Mwanza Gulf area of Lake Victoria. 9 pp. Zoologische Mededelingen 82: 167-175.

 Oijen M. J. P., Loots G. M. P., 2012: An illustrated translation of Bleeker’s Fishes of the Indian Archipelago. (Cyprini) Part II. 469 pp. Zoologische Mededelingen Leiden 86(1): 1-469.

 Oijen, 1992: Haplochromis howesi spec. nov., a crab and fish eating cichlid from Lake Victoria. 19 pp. [81177] Zoologische Mededelingen 66(40): 561-579.

 Olexa A., 1962: Über die Haltung des Bunten Zwergchamäleons Microsaurus pumilus Daud. 9 pp. (in German). [M52] Aquarien und Terrarien: 33-41.

 Oliva-Paterna F. J., Minano P. A., Torralva M., Fernández-Delgado C., 2007: Estrategias reproductoras de Barbus graellsii y Chondrostoma miegii (Pisces, Cyprinidae) en el río Cinca (NE Península Ibérica). [Reproductive strategies of Barbus graellsii and Chondrostoma miegii (Pisces, Cyprinidae) in the Cinca River (NE Iberian Peninsula)]. 18 pp. Zoologica Baetica 18: 3-20.