Connection
Frontispiece from The Continental Harmony, 1794
William Billings

Distinctive titles:

The piece has a distinctive or unique title such as Schubert's Winterreise.
 

• Remember to limit your search to scores.
   
• Use the "Title" search which can be found in the drop-down menu of the "Keyword" search box.
   
• "Keyword" searching is the simplest approach, but it is less specific because it searches author, title and subject all at the same time.
   
• Using the "Title" search box, when you know the title, can save you time in the long run.

Non-distinctive titles:

The piece has a very general or non-distinctive title such as symphony or quartet.

• Remember to limit your search to scores.

• Use the "Keyword" search or "Title" search.
   
• Opus numbers can be helpful for identifying such titles.  For composers whose works have been indexed using special music catalogue numbering systems, such as the Köchel-Verzeichnis (Köchel Catalogue) for Mozart's work, use that number instead of an opus number. For instance "Mozart K 317."
   
• Beware.  Sometimes opus numbers, Köchel numbers, and other music catalogue index numbers can be printed with inconsistent punctuation from one edition to another. 
  You can encounter "opus 18" or "op. 18" or "op.18." 
  You can also encounter "K 317" or "K. 317" or "KV 317." 
  These variations can influence your search results. To ensure you are getting all the variations we recommend using a search with just the opus or indexing number and the composer's name.
  • "Mozart 317" for Mozart's Mass in C major, K.317.
  • "Beethoven 18"  for Beethoven's Quartet op. 18, no. 4 : mixed clarinet quartet.
     
• Scores can be published in many different languages so searching the title in English sometimes misses other editions.  (Even key signatures can be written in different languages.)  Searching by the composer's name along with opus numbers or index numbers, as described above, can help with this.
  
  Here are examples of variant titles for the same Mozart mass.  They all share the same Köchel number.  Doing a keyword search for "Mozart 317" would find all of these.
  • Mass in C major, K.317
  • Missa Brevis in C, K. 317
  • Coronation Mass, KV 317
  • Krönungsmesse, K 317

• Where to find Opus numbers and other indexing numbers?
  • Oxford Music Online / Grove Dictionary of Music and Musicians - Search for composer's name and choose "works" tab for list of works. These entries have been reviewed by music specialists and scholars and should be highly accurate.
  • Wikipedia provides lists of works for many major composers in the composer's article.  It is not always a complete resource, but can be handy for quick lists of compositions.