I am trying to find out what resources I need to look into to find out when this last sentence in luke was added to the lectionary.
I'm not sure the question can be answered with knowing:
However, if you are asking about scholars who believe the sentence to be a later addition to the Bible text unrelated to the lections, I don't know anything about timing but C.H. Dodd, Raymond Brown, and Gerd Theissen all fit the bill.