A couple of books available from CMAA can provide info about the history of hymns and other chants:

Britt's "Hymns of the Breviary and Missal"
Johner's "Chants of the Roman Gradual"

They're both available as PDF downloads from our website's resource page, and
also in print through the CMAA shop.

There are two books by J. Vincent Higginson both were published by The Hymn Society of America that deal specifically with the history of hymns and hymnals (1850-1950). They are available through eBay, Amazon and hard to find online book stores such as AbeBooks. "History of American Catholic Hymnals-Survey and Background" pub. 1982 and "Handbook for American Catholic Hymnals" pub. 1976.

Also "Daniels Hymnologicus Thesaurus"

Another is "Annotations of the Hymnal"

And "The Caecilia" magazines on the CMAA website. They are a great resource.

Thank you, dear brothers! These are exactly what I was hoping to find. What a wealth of knowledge! Thank you.

Now I wish you all a most Blessed and Peaceful Easter! Alleluia!

The index of the Liber hymnarius (Solesmes) lists the century of composition and author if known.

The Triplex is under copyright, so it's not going to be on-line any time soon. And it doesn't show manuscript neumes for the Mass Ordinary anyway, but the 1974 GR does give a century indication for most of the chants.

Many thanks for that, Mad - I've often wanted reference to the adiastematic neumes of the ordinaries. One would think (in vain) to find them in Graduale Triplex!