Try all the Teaching Company and Modern Scholar series. I think a lot depends on whether you enjoy the presenter/scholar - and the topic of course. This one is very good based on her famous book - Paris 1919: Six Months That Changed the World. Moreover, both these series (TTC and TMS) should be free at your local libraries. Frankly, I find Carlin more entrepreneur than scholar. https://www.amazon.com/Modern-Scholar-Months-Changed-Conference/dp/B001EBHFES