Musical works and composers will frequently have more than one name. The Magic Flute is an excellent example.
In German text his name is spelled Die Zauberflöte.
Transliterated it loses the umlaut over the "o"
Translated we say The Magic Flute.
How does this affect your searches? It means that when you search for The Magic Flute within the online catalogue, you may not receive listings for Die Zauberflöte. In order to find all the resources that could be helpful to you, you need a uniform title.
There are a few ways to go about this.
1. For opera and other titles assigned by the composer: Search in the original language. If you don't know the original language type what you do know and look through the other search results that pop up for a foreign language title. Or you can google/wikipedia it to find the original language title, but make sure whatever source you use cites a legitimate source. Examples: La Nozze di Figaro (instead of The Marriage of Figaro), Prélude à l'après-midi d'un faune (instead of Prelude to the Afternoon of a Faun), and Noches en los jardines de Espana (instead of Nights in the Gardens of Spain).
2. For works categorized by form: Search by using the opus number and composer. If you don't know the opus number, search using the format Composer, Form, Instruments, Key of Work. When searching for a symphony, the orchestra is implied so you just need to list the symphony and the number. If you know that a work might be a sonata or a sonatina you can search with an asterisk so that the catalogue can finish the word for you. When you search Clementi, Sonat*, Piano, Db, catalogue will find both sonatas and sonatinas.
3. For non specific works: search by form, performance medium or mixed form. If you just want to find some concertos by Bach and you don't have a preference on which, simply search for Bach Concertos. If you are looking for chamber music by Schubert, search for Schubert Chamber Music. If you just want to find any type of work by Gershwin, search for Gershwin works.
Got a tune stuck in your head? Use these books to find out what it is.