Information on this subject will be found in Hawkins's _History of
Music_, vol. i. p. 398. _et seq._; Burney's _History of Music_, vol. ii.
p. 131. Busby's _Dictionary of Music_; John Gregory's _Works_
("Discourse declaring what Time the Nicene Creed began to be Sung in the
Church"), and in Staveley's _History of Churches in England_.