Reference sources are a great place to start your research when you need to gather initial information about a topic or get a rough overview of a subject so you can decide what areas to research further. Reference books and online tools are also excellent for looking up a quick fact, definition, or date, and they will often direct you to more sources.
If none of the recommended resources are quite what you're looking for, try a search in the Library catalog for the subject you're researching and "reference", "handbook", "guide", or "companion" to see what reference materials we might have on the subject. Remember that you can always reach out to a librarian for help if your search doesn't turn up promising results!
A Dictionary of Hymnology: Setting forth the Origin and History of Christian Hymns of all Ages and Nations; Vol. 1 and 2
by
John Julian, D.D.
The Hymnal 1982 Companion; Vol. 1-4
by
Raymond F. Glover
Analecta hymnica medii aevi
Spirituals : a multidisciplinary bibliography for research and performance
by
Abromeit, Kathleen A.