I had a professor who was very good about that stuff. He would emphasize the need to get multiple sources. He had several examples the most recent being the anti-gun book “Arming America” in 2001… prof pointed out that the guy cited records that had been destroyed long before the author was born and no copies survived. There were examples from Greece and Rome. For example the Spartans testing sickly babies off a mountain was first mentioned by Plutarch… 800 years later. Then there was the story of the establishment of the Roman Republic… the Etruscan King that was killed for raping the woman was actually one of the first senators… and the source is Livy who wrote about it centuries later.