I am just listening to lecture 2 and have found an online version of ‘History Begins at Sumer’ on this site: http://archive.org/details/HistoryBeginsAtSumer
The PDF version is a bit chopped up but the ‘Read Online’ version seems to work ok. I thought I’d mention this in case anyone wants to put a link to the online version in the Lecture 2 materials to complement the Amazon link.
(Btw I’m not 100% sure about the copyright status but I figured archive.org is a fairly mainstream site. If the online version breaches copyright then ignore this post 🙂