^ Yeah Londo's videos are well worth the time too :-)
Lots of resources out there.
Does anyone know off hand any credible quote from a professor or someone which I can show to the elders?
It won't matter. 'The professors are wrong, see. They go by profane, secular chronology while we JWs go by God's Word the Bible and its chronology.' That misunderstanding can be squashed but this'll be the come-back.
Anyway, the burden of proof is on the elder - if you really want to go down that road with him (it'll be long haul if he's honestly willing for a two-way discussion to happen). Ask him why JWs are alone in the 607 date when ALL respected authorities say 587/6 BCE for Jerusalem's destruction. Get him to do the research. Get him doing the work and provide you with sound evidence for the 607 date.