Accurate information is essential in preparing a professional level program. While we all may use Wikipedia for quickly finding information on-the-fly, when it comes to putting together a recital program or writing a research paper, unattributed, crowdsourced articles are usually not the best sources. There are many established authoritative resources that are far more reliable.
Strangely enough, sometimes the most misleading source of information can be the music itself. It is not uncommon to consult four different editions of the same piece and find four different variations on the title of the work. You may also find that pieces found collections can have very incomplete information. It is not very precise or informative to list a work as "Minuet" in your program when the composer may have written a dozen minuets or if it is a movement from a larger work. Working from older editions, you may find a wide variety of spellings of composer's names. You may even encounter a situation where more recent research has revealed that a different composer actually wrote the work.
Some good places to begin researching your repertoire are listed below.
The leading online resource for music research. Use Grove Music Online to establish full names of composers, establish accurate birth dates, and to identify individual compositions with a composer's total oeuvre.
Includes the fulls texts of The New Grove Dictionary of Music and Musicians, 2nd ed. (2001), The New Grove Dictionary of Opera (1992), and The New Grove Dictionary of Jazz, 2nd ed. (2002), along with various update and emendations. The contents of two new print publications are currently being added: The Grove Dictionary of American Music, 2nd ed. (2013), and The Grove Dictionary of Musical Instruments, 2nd ed. (due out in 2014).
Grove Music Online is accessed via the Oxford University Press music search portal, Oxford Music Online, which allows you to simultaneously search The Oxford Dictionary of Music and The Oxford Companion to Music, as well as Grove. Both of these resources can provide valuable information, but Grove is considered to be the most authoritative.
Use Grove to establish birthdates and reconcile name variants.
Composer work lists found within Grove composer entries may be helpful for determining proper work titles, opus or thematic catalog numbers (e.g. BWV numbers for J.S. Bach or D. numbers for Schubert), or indentifying the source of a work with a particularly generic title. The following example is from the work list for Franz Schubert.
Library of Congress Authorities
Libraries have developed methods for grouping together items and data representing identical content both in their catalogs and on their shelves. This way all versions of the some composition will be assembled under a commonly agreed upon format no matter how the publisher of a particular edition choose to designate it. The Beethoven piano sonata you would list in your program as "Sonata No. 14 in C# Minor, Op. 14, No.2" may have been published as Sonate für Pianoforte, Mondschein or Sonata quasi una fantasia or Moonlight Sonata or Clair de lune and so on. Librarians create what are known as "authority records" to document standardized forms for titles, subject headings, and names. An authority record with also often document the research that was done to verify the information.
You can search the national authority files to see these authority records. Since these records are created for the purpose of library filing, the title forms are not necessarily how you would want them to read in your program, but some very valuable historical and bibliographic information about your composers and music may be found here. Search names with the search type "Name Authority Headings". Search composition titles with the search type "Keyword Authorities (All)" using the composer's last name together keywords from the title or an opus or thematic catalog number. Seek out the "Authorized Heading" in your search results.
In the following example, a search for the Pergolesi opera Il Geloso Schernito led to an authority record that reveals that the composer actually is Pietro Chiarini (100 field). Pergolesi is listed among three non-valid cross-reference headings (400). Research that was done to create this record appears toward the bottom (670) where we find that Grove Music Online indicates that although the work has formerly been attributed to Pergolesi, it is now believed to be by Chiarini.
There are a large number of print sources available in the Music Library and in Campbell Library that may be useful in researching information for your program.
Biographical Dictionaries will contain short entries on composers, along with birth and death dates, and sometimes a list of major works. One of the major biographical dictionaries for music is Baker's Biographical Dictionary of Musicians. In addition to the most current release of this publication, the library retains some of the earlier editions. These are sometimes good sources for finding more obscure names that were not carried forward into later editions.
Most biographical dictionaries may be found in the Music Library reference section under Ref. ML 105.
Bibliographies on a variety of topics such as chamber music, songs and arias, or repertoire for individual instruments may be found in the Music Library reference section under Ref. ML 128.
Bibliographic guides to research the lives and works of individual composers may be found in the circulating stacks of Campbell Library. A major series of these is Garland Composer Research Manuals.
Thematic Catalogs may be used to identify or find information about a piece of music. Most major composers have had thematic catalogs compiled for their music. Musical incipits (a short musical example, usually of the opening theme or measures) are usually included as aid in identifying works. A well known example of a thematic catalog is the Köchel catalog of the works of Mozart.
Thematic catalogs are shelved in the Music Library reference collection under Ref, ML 134.
Collected editions of individual composers' complete works are shelved in the Music Library's reference section under Ref. M 3. These large, multivolume sets are critical (or scholarly) editions usually produced, sometimes over decades by committees of prominent scholars. These publications are based on thorough study of primary sources, such as autograph manuscripts, sketches, early editions, etc. The editions often include comprehensive critical commentary that may reconcile discrepancies in the publication record of a composition.
Some of the larger of these sets owned by the Music Library are those for Bach, Beethoven, Brahms, Debussy, Gluck, Handel, Haydn, Mozart, Mussorgsky, Schoenberg, Schubert, and Wagner, along with a variety of smaller editions covering other composers.
Wikipedia
Although Wikipedia cannot be considered an authoritative source, there are times when you may find it a useful starting place for research. For contemporary music, the articles in Grove Music Online are not updated frequently enough to be as complete as what you may find in Wikipedia. As an example, the Grove article on the composer Michael Daugherty consists of a brief timeline of his education and teaching career followed by a 17-line description of his musical style and selected compositions up until the year 2000. The article was last updated in 2001. The Wikipedia entry, in contrast, has a much longer and detailed text covering his personal life, education, and career, along with a number of pictures, and a complete list of compositions contining up to commissioned works scheduled to premiere in 2015. Inversely, regarding the respective articles on Mozart, Wikipedia's article is slightly more substantial than the Daugherty one, while Grove's runs to 28 pages (in the print version), not counting another 43 pages for the works list and bibliography.
It is important though to judge sources on what they actually present. Back to the case of the two Michael Daugherty articles: despite its brevity, the Grove article does contain a small amount of description of the composer's style, while the Wikipedia article is mostly a list of objective facts. Where the Wikipedia entry does show its greatest value is in the list of sources in the footnotes, references, and external links. The researcher must excercise their own judgement in determining the veracity of each of these sources.
Websites
Among online sources for music, a composer's personal website would have to considered authoritative on his or her life and music. A publisher's website maybe be less so, but can probably be considered particularly reliable for contemporary music. Another dependable online source may be a university, research center, foundation, or other institutions website if the subject is within the organization's mission or expertise.
Examples:
Composer's Offical Website: Jake Heggie Website
Publisher Website: Music Sales / Aaron Jay Kernis
Instituational Website: Beethoven Center (San Jose State University)