A series of articles (ongoing, I think) on exclusive Psalmody from Rev. Daniel Kok, a RPCNA pastor in Calgary, Alberta Canada. These are helpful.
Exclusive Psalmody and Singing Jesus' Name
Exclusive Psalmody and "a new song"
Exclusive Psalmodists and the singing of Psalms
Exclusive Psalmody and the use of Old Covenant language
Exclusive Psalmody and singing other songs in Scripture
"Psalms" and Psalms, hymns and spiritual songs
