Does anyone know of a source that discusses as a group the songs in Two Noble Kinsmen (attr. W.Shakespeare and John Fletcher) in relation to traditional folk ballads - such as the Child or Roud numbers or broadsides to which they may be related, and evidence as to whether these were composed by the authors of the play or pre-existing traditional songs?   

I've found comments here and elsewhere about individual songs referenced in the play but there are a great number, particularly as sung by the Jailer's Daughter.

Many thanks,
Pamela