If you have a newspaper clipping that is undated and unsourced, flip it over. Anything can be a potential clue as to location or date, even classified ads.
One obit I found in a set of clippings had a date, but no name of the newspaper. Flipping it over I found the classified ads. The phone numbers and street names told me it was from a nearby town of 40,000 and not one of the small towns near where the relative actually died.