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 

 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.

 Olson L., Violani C., 1995: Some unusual hybrids of Ramphocelus, with remarks on evolution in the genus (Aves: Thraupinae). 16 pp. (in English). Bolletino del Museo regionale di Scienze Naturali – Torino 13(1): 297-312.

 Olson S. L., Violani C., 1995: Some unusual hybrids of Ramphocelus, with remarks on evolution in the genus (Aves: Thraupinae). 16 pp. 

 Orgeira T. J. L., 1995: Seabird observations of the Argentine Atlantic shore between Tierra del Fuego and Buenos Aires. 11 pp. 

 Orgeira T. J. L., 1995: Seabird observations of the Argentine Atlantic shore between Tierra del Fuego and Buenos Aires. 11 pp. (in Italian). Bolletino del Museo regionale di Scienze Naturali – Torino 13(1): 105-115.

 Ortlieb R., Helbra, 1981: Die Sperber. Die Neue Brehm – Bücherei 523. 144 pp. 

 Paine J. H., 1917: An asymmetrical bird-louse found on three different species of Troupials. 3 pp. 

 Palmer W., 1890: Notes on the birds observed during the cruise of the United States fish commission schooner Grampus in the summer of 1887. 17 pp. 

 Papadopol A., 1960: La biologie d’hiver de certains oiseaux. Observations faites dans la région de Bucarest. 30 pp. 

 Papadopol A., 1965: Contributions a la connaissance de la biologie de la couvaison et de la mitrition des poussins chez Parus major L. (Aves). 16 pp. 

 Papadopol A., 1965: Contributions a la connaissance de la systématique répartition et biologie d’Alcedo atthis (L.) en Roumanie. 14 pp. 

 Papadopol A., 1965: Essai sur l’ornithofaune du lac Calarasi et du sud-ouest du marais Borcea (marais Ialomita). 36 pp. 

 Papadopol A., 1965: Le moineau espagnol Passer hispaniolensis hispaniolensis (Temm.) en Roumanie (Aves, Passeridae). 5 pp. 

 Papadopol A., 1968: Considerations on the dynamics of some birds in connection with the Danube and Black Sea shore in Romania. 11 pp. 

 Papadopol A., 1968: Les charadriiformes de Roumanie (II). Contributions concernant l’écologie des espéces couveuses. 17 pp. 

 Papadopol A., 1970: Les charadriiformes de Roumanie (III) études concernant la nourriture, les relations trophiques et le vol. 22 pp. 

 Parkes K. C., 1958: Taxonomy and nomenclature of three species of Lonchura (Aves: Estrildinae). 15 pp. 

 Parrini R., Raposo M. A., 2010: Aves se alimentando de Alchornea glandulosa (Euphorbiaceae) na Mata Atlantica do sudeste do Brasil – Birds feeding on Alchornea glandulosa (Euphorbiaceae) in the Atlantic Forest of southeastern Brazil. 9 pp. (in Portuguese). Boletim do Museu de Biologia Mello Leitao (N. S.) 27: 75-83.

 Parrini R., Raposo M. A., 2012: Comportamento de forragaemento de Xiphocolaptes albicollis (Passeriformes: Dendrocolaptidae) na Floresta Atlantica Montana do sudeste do Brasil. Foraging behavior of the white-throated woodcreeper Xiphocolaptes albicollis (Passeriformes: Dendrocolaptidae) in the Montane Atlantic Forest of southeastern Brazil. 15 pp. (in Portuguese).. Boletim do Museu de Biologia Mello Leitao, (N. S.) 29: 65-79.

 Pascovschi S., 1965: Über die Forms ersten Handschingebei den Entenarten der Gattung Anas. 5 pp.