Ó Flaithbheartaigh and Ó Dubhda would have obtained them from Dubhaltach Mac Fhirbhisigh, whose family created and preserved the book.
Ó Flaithbheartaigh and Ó Dubhda would have received the manuscripts from Dubhaltach Mac Fhirbhisigh, whose family had a long history of creating and safeguarding written works.