On Wed, 7 Feb 2018, Jürgen Spitzmüller wrote:
They come from the BibTeX style file (*.bst).
Jürgen, This explains why I did not see them; there's no .bst file in the document's or jabrefdb.bib directories. I wonder why this appears for only one or two files since I've been inserting jabref citations in lyx documents for several years now. Thanks very much for showing me where the issue originates. Best regards, Rich