The New Grove Dictionary of Opera

It is the largest work on opera in English, and in its printed form, amounts to 5,448 pages in four volumes.

[1][2] The dictionary was first published in 1992 by Macmillan Reference, London, and edited by Stanley Sadie.

[4] The work contains contributions from over 1,300 scholars, with 11,000 articles in total, covering over 2,900 composers and 1800 operas.

[3] The final volume includes four appendices: an index of principal role names in 850 notable operas; an index of incipits of arias and ensembles (first line only, no musical examples); a list of contributors; and illustration acknowledgements.

[8][9] The dictionary was originally available online in a web version of its original form[10] but has now been merged as part of Oxford's Grove Music Online which comprises the range of Grove Dictionary titles with some ongoing revisions.