Operas 52,517 Orchestral music 16,145 Ouvrages illustrés 14,583 Outlines, syllabi, etc 14,031 Ouvrages avant 1800 11,679 Observations 10,925 Oral histories (literary works) 10,857 Oral histories 9,739 Organ music 8,565 Outlines and syllabi 8,406 Overtures 7,723 Oratorios 5,893 Oral histories (document genres) 4,836 Ordination sermons 3,599 Ouvrages pour la jeunesse 3,525 Online resources 2,456 Ouvrages illustrés 2,354 Orchestral music, Arranged 2,331 Orthographic drawings 2,020 Operettas 1,819 Ouvrages de référence 1,780 Ouvrages de vulgarisation 1,705 Ouvertures (Musique) 1,662 Online databases 1,578 Outline 1,425 Outdoor books 1,366 Outline maps 1,240 Ornate types (Type evidence) 1,161 Observers' manuals 1,132 Occult fiction 1,074 Outlines 1,058 One-act plays 1,005 Obituaries 811 Ouvrages de controverse 717 Original art 709 Officers' handbooks 701 Original cast recordings 630 Online-Publikation 593 Oral interpretation of poetry 560 Orchestral excerpts 543 Opera adaptations 504 Odes 502 Octavo format (Printing) 471 Offset lithographs 395 Oratory 373 Opera films 361 Old-time music 311 Opracowanie 289 Opera 281 Ouvrages apologétiques 281 Onitsha market literature 246 Official gazettes 243 One-page folding zines 236 One-sheet posters 216 Ornament drawings 204 Office du soir (Musique) 202 Oral history 186 Occasional poems 179 Onlays (Binding) 175 Optical disks 169 Offertories (Music) 154 Occasional sermons 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 Oregon authors 112 Ouvrages avant 1900 112 Open form music 111 Orations 106 Opéras de chambre 100 Organa 99 Orders in council 95 Original covers (Binding) 93 Obras ilustradas 92 Open access resources 87 Opera television programs 87 Outtakes 87 Occasional speeches 84 Obras anteriores a 1800 81 Osgoodiana 73 Online-Ressource 71 Oral histories (literary genre) 64 Ouvrages avant 1850 64 Octavo 59 Orphans Court records 58 Offertoires (Musique) 57 One-page folding-zines 55 Office du matin (Musique) 53 Open educational resources 52 Orchestral parts 51 Oriya fiction 51 Onlays 50