You are looking for sheet music in a particular genre and/or for a particular instrumentation?
This is rather complicated in the Utrecht University Library catalogue, because this catalogue is not primarily meant for performing musicians. Preferably use the name of a composer in your search; combine it strategically with other elements. Consider your search terms well. Try to be exact, but not to the extent that you might miss relevant results.
Searching for instrumental music
Example:
You are looking for the piano sonatas by Joseph Haydn (1732-1809).
Enter at Search in All Fields: joseph haydn sonat* A list of results is shown. Click on Filter, go to Material Type and choose the option Printed music. Now a few dozen titles remain: not all for piano, but it is easy to see what titles can be played on the piano and what titles cannot.
Why "sonat*" and not "sonates"?
The plural *sonates* is only used in Dutch and French. Now you will miss all editions that have been published in other languages. And that's a lot of editions.
Why not add the search term *piano*?
The word "piano" is not a usual term in all modern languages (for instance in German: Klavier.) Besides, most musicologists are of the opinion that the term "piano" should not be used for music from this period. So if you add "piano" to your search terms, you will miss two categories of editions:
1. publications (especially in German) in which another word is used for "piano",
2. editions by musicologists who do not agree with the word "piano" in relation to this kind of music. The search results you get by entering joseph haydn sonat* and by filtering on Printed music are not that numerous; you can easily browse through the list.
Similar questions might occur in relation to other indications for instruments (for instance: harpsichord/Cembalo/clavecin; flute/Flaute/traverso).
Searching for vocal or vocal-instrumental music
Searching for vocal or vocal-instrumental music within a particular genre and/or for a certain instrumentation has its limitations in the Utrecht University Library catalogue. Some vocal works (but not all) are indicated by genre such as: madrigal, chanson, cantate, song, motet, mass. Also these terms occur in different languages and forms (singular, plural).
Example 1: You are looking for the sheet music of the madrigals by Claudio Monteverdi. Enter at Search in All Fields: monteverdi madrig*. A list of results appears. Now click on Filter, go to Material Type and select Printed Music.
Example 2: you are looking for the sheet music of the cantates by Johann Sebastian Bach. Enter at Search in All Fields: bach johann cantat* A list of results appears. Now click on Filter, go to Material Type and select Printed Music.
The original music notation noted down before 1800 often differs from the modern music notation. It is important for researchers to be able to study the original notation as well. Utrecht University Library has many of these original notations on microfilms, microfiches or photos. Usually the material consists of pictures from old manuscripts or early printed works from other libraries. These microfilms, microfiches and photos can be viewed in the University Library City Centre. You can also make print-outs of these microfilms and microfiches, but for that you need to go to the University Library. Please ask library staff for help.
If you are looking for such an original notation, you know from the literature which manuscript or early printed work you want to see. The library catalogue will tell you if the library owns a picture of the notation. Proceed as follows:
For instance, you are looking for pictures of the manuscript Rome, Biblioteca Casanatense Ms 2856. At Search in All Fields enter: Casanatense 2856. This will immediately lead to the right result.
You can also find out which works of a particular composer can be studied in the original notation. For instance, proceed as follows for the composer Josquin des Prez (ca. 1450-1521). Enter at Search in All Fields: Josquin. Next go to Material Type and filter on Audio-visual. Now you will get the microfilms of old manuscripts with works by Josquin. These manuscripts often contain works by more than one composer; that is why you need to enter Josquin at Search in All Fields (and not at Author).
There are different kinds of sheet music. The most important are: score, part, piano excerpt, facsimile.
A score (plural: scores) contains the full representation of a musical work. All voices and instruments are noted down fully, usually one below the other, in a fixed order. Scores can differ greatly in volume and complexity. The score for a work for orchestra is often voluminous and complex: after all, an orchestra consists of dozens of instruments and all these instruments are noted down one below the other. The score of a work for a smaller ensemble is simpler. In the catalogue the scores are indicated as follows:
Pa-2 (large score, folio size)
Pa-4 (large score quarto size)
Pa-8 (study score, octavo size, also called "pocket score".)
A part contains the musical notation of one voice (vocal or instrumental) of a musical work. In the Utrecht University Library not many parts are available; the collection mainly focusses on lecturers, students and researchers, not so much on musicians.
Vocal-instrumental works (operas, oratorios, musicals, cantatas etc.) are not only published in the form of scores, but also as piano reductions. A piano reduction contains all vocal parts, besides a reduced version of the instrumental parts. This reduced version is noted down in the form of a piano part or organ part. In this way it is easier to accompany the vocal parts. Also, piano reductions make it easier to study a work. In the catalogue they are indicated by KL UITTR.
"Facsimile" means "make the same". The term "facsimile-edition" indicates photographic (and so: exactly the same) reproductions of special sheet music editions and manuscripts: for instance a photographic reproduction of sheet music published before 1800, or of a sheet music manuscript in the handwriting of the composer himself (a so-called autograph). Facsimiles are important because they give researchers easy access to these remarkable sheet music prints and manuscripts
After 1945 new forms of musical notation were produced, for instance "graphical" notation, in which use is made of other visual symbols than the traditional musical notation, as well as of several forms of "free" notation (without pitch, bars and/or length). Also mixed forms occur. In these musical notations the distinction between score and part may not always be clear.
If you have not found anything with the methods described above, you can almost always check a reference work to find out if there is a (reliable) edition of sheet music of the composition you are looking for.
Go to Oxford Music Online; only select "Grove Music Online", choose "Advanced Search", search with "Entry title" for the article about the composer in question, click on "Works"(left column, at the bottom). Now you will get an overview of the complete works of the composer. In this overview you will see if a work is published in a modern edition. The used abbreviations are explained at the top of the list of works. If this is not the case, you can find an explanation under Tools and Resources (at the bottom of the page) and next on Abbreviations.
Less known music composed before 1800 is often not available in print but only as manuscripts or handwritten copies. Those manuscripts can be found in all kinds of libraries. For many composers they have been well listed. In the overviews of Oxford Music Online you will also find where these manuscripts can be found, in case there are no printed editons available of the work in question. The locations are indicated by abbreviations. You will find an explanation of the abbreviations under Tools and Resources (at the bottom of the page) and next on Abbreviations.
Your search may become considerably simpler if you already know what you are looking for. Many compositions have a unique number: a so-called Werkverzeichnisnummer or an Opus number.
In the box Searching for sheet music in the Utrecht University Library, examples of two compositions were already given:
- the sonata for piano and violin KV30 by Wolfgang Amadeus Mozart. KV 30 means Köchel-Verzeichnis, no. 30. In 1862, the music scholar Ludwig von Köchel published this numbered list of Mozart's compositions. This list has been revised and complemented a few times. Mozart's compositions are usullay indicated by the number they have on this list.
- the cantata Herr, gehe nichts ins Gericht BWV 105 by Johann Sebastian Bach. BWV 105 means Bach Werke-Verzeichnis, number 105. In 1950 the music scholar Wolfgang Schmieder published this numbered list of the compositions by Johann Sebastian Bach. Bach's compositions are usually indicated by the number they have on this list.
Many composers have such authoritative lists (thematic catalogues, Werkverzeichnisse). Usually they are classified by genre/instrumentation and within these classes ordered chronologically. In Grove Music Online these lists are given at the end of the articles on composers. The number of a certain composition is not hard to find. The thematic catalogues are also available as books in the Utrecht University Library (enter the name of the composer at Person as Subject); the books contain a lot of extra information, such as the musical notation of the beginning of the composition and a complete overview of the manuscripts and editions seen as sources for that particular composition.
If there is no Werkverzeichnis available for a composer, his or her works often have so-called opus numbers (the Latin "opus" means "work"). Opus numbers have often been given during the life of the composer, either by himself (or herself) or by sheet music publishers. They have a more or less chronological order (they are not classified by genre/instrumentation.) Opus numbers are often less unambiguous than Werkverzeichnis numbers. They mainly served a practical goal (without scholarly pretentions), so confusion may sometimes arise. Sometimes different compositions have accidentally the same opus number (so the number occurs more than once in the work of the composer); and composers may also have readjusted previous numbers assigned by themselves.
Werkverzeichnis numbers and opus numbers help you to make your search more efficient.
Petrucci Music Library (IMSLP) 
Overviews by composer
Johann Sebastian BACH
Bach Digital (contains digital reproductions of the music autographs)
Ludwig van BEETHOVEN
Beethoven-Haus Bonn: digitales Archiv (contains digital reproductions of the music autographs)
Johannes BRAHMS
Digitaler Notenschrank (autographs and scanned old editions of all opus numbers)
Alphons DIEPENBROCK
Muziekmanuscripten van Alphons Diepenbrock (all Diepenbrock autographs from the collection of the Nederlands Muziek Instituut (Dutch Music Institute), digitised for the project Het Geheugen van Nederland (The memories of the Netherlands)
George Frideric HÄNDEL
Handel Werke (the digitised version of the series published by the Deutsch Händel-Gesellschaft between 1858 and 1902, ca. 100 volumes)
Händel-Haus Halle (digitised versions of manuscripts, editions and literature available here)
Franz LISZT
Franz Liszts musikalische Werke (the digitised version of the series published by the Franz Liszt Stiftung between 1907 and 1936. The series consists of 34 volumes, has never been completed but contains the larger part of Liszt's works)
Felix MENDELSSOHN-BARTHOLDY
Mendelssohns Werke (the digitised version of the Gesamtausgabe published by Julius Rietz between 1874 and 1877 (at Breitkopf & Härtel)
Wolfgang Amadeus MOZART
NMA Online (the digitised version of the Neue Mozart-Ausgabe, ca. 125 volumes)
Mozart's letters (digitised edition of the Mozart letters in four languages)
Franz SCHUBERT
Schubert-Autographe (contains digital reproductions of more than 500 music autographs and letters)
Robert SCHUMANN
Robert Schumann's Werke (the digitised version of the Gesamtausgabe published by Clara Schumann and Johannes Brahms between 1879 and 1893 (at Breitkopf & Härtel))
It is not difficult to imagine that copyright free sheet music should be found "somewhere" on the Internet. Copyrighted sheet music is a different story.
Remember that sheet music is often offered in PDF format. So use the options of Google to limit your search to PDFs.
Another problem is that there are often transcriptions around. For instance, there are hundreds of variations and transcriptions of the Canon of Pachelbel to be found.
So it makes a large difference if you are searching for a musical work to be played by a particular instrument or if you are searching for the original notation by the composer.
If you haven't found what you were looking for, you have several other options within the Netherlands.
In NCC/PiCarta the catalogues of all Dutch university libraries and a number of important other libraries are joined toghether. In this national catalogue you can also find information about sheet music. Proceed as follows:
Select Advanced Search, at Material Selection untick all the boxes, except Music, enter your search terms. We recommend you to search by a combination of words: you will only have to combine a few well-chosen terms to get an exact result. For instance:
You are looking for sheet music of the Beatles song Yellow Submarine. Enter beatles submarine at All Words. The result is a list of collected works in which you will find this song.
You are looking for sheet music of Cantique de Jean Racine by the composer Gabriel Fauré. Enter Fauré at Author; enter Racine at title words, click on Search. The combination of these two terms is so unique that you immediately get the right result.
The MCO (Hilversum) contains one of the largest sheet music collections in Europe. In particular the collections of chamber music and popular music are special. The collection of popular music also contains the full archive of arrangements, written for the Dutch radio ensembles from ca. 1940 onwards.
Unfortunately the MCO closed its doors on 1 August 2013. A visit to the library is no longer possible. What is going to happen with the collections is still not clear. For the time being, the catalogue (not included in PiCarta) remains available to anyone: a very valuable reference work. The catalogue offers excellent options to search by instrumentation and by keyword (Christmas, spring, madrigals....)
Pianofiles
On this site you can ask for or exchange sheet music with people from all over the world. All you need to do is create an account! However, do not come empty-handed, you must have something to offer in exchange. The emphasis is on popular music.