Negro spirituals are best preserved through live performance, archived scores or recordings, and published bibliography. A few sources are listed here:

Classical Vocal Reprints_ Recital/Concert Music Scores (http://www.classicalvocalrep.com/)

Jacqueline Butler Hairston_ Composer/Arranger/Pianist (http://www.jbhproductions.com/)

Videmus _ African American Music Source (http://www.videmus.org/)

Kevin J. Miller_ Pianist/Collaborator/Coach (http://www.kevinmillerpiano.com/)

The Spirituals Project at University of Denver (www.spiritualsproject.org)

The American Spiritual Ensemble (http://www.americanspiritualensemble.com/)

Hal Leonard Music Print Publisher (https://www.halleonard.com)

GIA Sacred Music Resources (http://www.giamusic.com/)