Operas 52,530 Orchestral music 16,144 Ouvrages illustrés 14,528 Outlines, syllabi, etc 14,029 Ouvrages avant 1800 11,705 Observations 10,923 Oral histories (literary works) 10,857 Oral histories 9,739 Organ music 8,565 Outlines and syllabi 8,400 Overtures 7,726 Oratorios 5,894 Oral histories (document genres) 4,836 Ordination sermons 3,600 Ouvrages pour la jeunesse 3,532 Online resources 2,456 Ouvrages illustrés 2,359 Orchestral music, Arranged 2,331 Orthographic drawings 2,020 Operettas 1,819 Ouvrages de référence 1,776 Ouvrages de vulgarisation 1,706 Ouvertures (Musique) 1,638 Online databases 1,579 Outline 1,425 Outdoor books 1,366 Outline maps 1,241 Ornate types (Type evidence) 1,161 Observers' manuals 1,131 Occult fiction 1,073 Outlines 1,058 One-act plays 1,005 Obituaries 812 Ouvrages de controverse 719 Original art 709 Officers' handbooks 700 Original cast recordings 629 Online-Publikation 593 Oral interpretation of poetry 560 Orchestral excerpts 543 Opera adaptations 504 Odes 502 Octavo format (Printing) 471 Offset lithographs 395 Oratory 374 Opera films 361 Old-time music 309 Opracowanie 289 Ouvrages apologétiques 282 Opera 281 Onitsha market literature 246 Official gazettes 244 One-page folding zines 237 One-sheet posters 216 Ornament drawings 204 Office du soir (Musique) 199 Oral history 186 Occasional poems 179 Onlays (Binding) 175 Optical disks 169 Occasional sermons 153 Offertories (Music) 153 Oil paintings (visual works) 153 Organ masses 153 Offprints 140 Operators' manuals 140 Ownership inscriptions 138 One-act operas 137 Orphans court records 136 Ouvrages de référence 130 Oil paintings 124 Occasional addresses 116 Ouvrages prélinnéens 116 Open form music 112 Oregon authors 112 Ouvrages avant 1900 112 Orations 106 Opéras de chambre 100 Organa 99 Orders in council 95 Original covers (Binding) 93 Obras ilustradas 91 Open access resources 87 Opera television programs 87 Outtakes 87 Occasional speeches 84 Obras anteriores a 1800 80 Osgoodiana 74 Online-Ressource 71 Oral histories (literary genre) 64 Ouvrages avant 1850 64 Octavo 59 Orphans Court records 58 Offertoires (Musique) 56 One-page folding-zines 55 Office du matin (Musique) 53 Open educational resources 52 Oriya fiction 52 Onlays 50 Orchestral parts 50