Score citations are very similar to book citations, with composers instead of authors. Consult the book tabs for information such as multiple authors, author with arranger, and publication information (multiple cities listed, no city listed, etc.).
It can be hard to find a publication/copyright date for scores. Look on the title page, on the verso (back side) of the title page, on the bottom of the first page of music, at the end of the preface, etc. If you cannot find one, write “n.d.” (which stands for “no date”).