The first attempt at a Dictionary of Operas was made by Leone Allacci, a learned Greek from the island of Chios, who became Librarian of the Vatican Library and published "Drammaturgia", a catalogue of all operas performed up to that date, in 1666. Since then a number of catalogues, dictionaries, and histories of Opera have been published in various languages, but the present monumental work of Dr. Alfred Loewenberg is the first, as far as I know, to arrange the material year by year in chronological, rather than alphabetical irder. It starts with the first of all operas, "La Dafne" composed by Jacopo Peri and produced at Florence in 1597, and ends with those produced in 1940. .... For every Opera named we are given the names of librettist and composer, as well as the name of the theater and the town in which the first production took place; but besides these bare facts we are often supplied with a vast quantity of subsidiary information, especially as regards the source of the plot, subsequent revivals in other cities and translations into various languages. ***Excerpt from Introduction by Edward J. Dent, October 1942***
This reference book is both useful and surprisingly fun to look through. It is a listing of operas, organized chronologically by the date of their first performances. Each entry includes: Title given in original language, with the original script below if the title has been transliterated for the main heading (as with Russian operas). Librettist, number of acts. Translations and cuts are noted if applicable. Notes about the opera. These are brief and varied and appear for most, but not all operas. Listings of other performances by language and date, with a city. These are usually the first performances per language and/or city. Names of translators. Information on revivals.
Annals of Opera, 1597-1940 also has a preface, indexes, and a brief historical survey of opera. I have found this book to be a very handy resource, as it puts together information that may be otherwise scattered and hard to find.