APA (7th ed.) Citation

Haydn, J., Haydn, M., Gruber, F. X., & Raml, F. Heiligste Nacht: Christmas music.

Chicago Style (17th ed.) Citation

Haydn, Joseph, Michael Haydn, Franz Xaver Gruber, and Franz Raml. Heiligste Nacht: Christmas Music.

MLA (9th ed.) Citation

Haydn, Joseph, et al. Heiligste Nacht: Christmas Music.