Rules for citing music scores in APA format are similar to those for citing books. Any mention of a music score within the body of your text requires a citation at the end of the sentence, including a bracket containing the last name of the composer, followed by a comma and then the year of publication, such as (Twain and Lange, 1997). You keep the bracket inside the sentence.
References for musical scores in APA also follow the format for books. Like book references, they begin with the last name of the composer, followed by her first name, the date of composition in brackets, followed by a period, the title of the work in italics, period, the location of the publisher, and then the publisher’s name. Add other clarifying details as necessary, such as the medium of the score, or an English translation of the title, if written in a foreign language. You may need to identify that one author is a composer while the other is a librettist, or that this piece is part of a larger series of music.