Operas 52,569 Orchestral music 16,148 Ouvrages illustrés 14,868 Outlines, syllabi, etc 14,031 Ouvrages avant 1800 12,050 Observations 10,927 Oral histories (literary works) 10,857 Oral histories 9,877 Organ music 8,565 Outlines and syllabi 8,404 Overtures 7,756 Oratorios 5,900 Oral histories (document genres) 4,836 Ordination sermons 3,601 Ouvrages pour la jeunesse 3,597 Online resources 2,458 Ouvrages illustrés 2,404 Orchestral music, Arranged 2,331 Orthographic drawings 2,020 Operettas 1,819 Ouvrages de vulgarisation 1,728 Ouvrages de référence 1,716 Ouvertures (Musique) 1,644 Online databases 1,581 Outline 1,425 Outdoor books 1,364 Outline maps 1,241 Ornate types (Type evidence) 1,161 Observers' manuals 1,131 Occult fiction 1,077 Outlines 1,058 One-act plays 1,007 Obituaries 815 Ouvrages de controverse 741 Original art 709 Officers' handbooks 700 Original cast recordings 630 Online-Publikation 594 Oral interpretation of poetry 568 Orchestral excerpts 543 Opera adaptations 504 Odes 503 Octavo format (Printing) 471 Offset lithographs 397 Oratory 373 Opera films 365 Old-time music 309 Ouvrages apologétiques 293 Opracowanie 289 Opera 282 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 190 Occasional poems 179 Onlays (Binding) 176 Optical disks 171 Occasional sermons 155 Offertories (Music) 153 Oil paintings (visual works) 153 Organ masses 153 Offprints 143 Operators' manuals 140 Ownership inscriptions 139 One-act operas 138 Orphans court records 136 Ouvrages de référence 134 Oil paintings 124 Ouvrages prélinnéens 120 Occasional addresses 116 Ouvrages avant 1900 116 Open form music 112 Oregon authors 108 Orations 106 Opéras de chambre 102 Organa 100 Orders in council 97 Original covers (Binding) 93 Obras ilustradas 91 Opera television programs 88 Open access resources 87 Outtakes 87 Occasional speeches 84 Obras anteriores a 1800 75 Osgoodiana 72 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 Online media 52 Open educational resources 52 Oriya fiction 52 Onlays 50