As an ex scientist I think the Elements is really useful but "The Folk Song Army" is perfect and "The Irish Ballad" is not half bad.

I was lucky enough to receive "Too Many Songs by Tom Leher with not enough drawings by Ronald Searle" for Christmas which has all the dots as well as the words of most of the songs from the three recorded collections. Strangely enough it also has some great drawings by Ronald Searle

BTW I think "Jamboree" was one of Paddy Roberts - another favourite