Thanks Mike. How the hell did I miss that one?

BTW., and re your review There is an article about the old-timey yodel in one of the editions of Tony Russell's Old Time Music. I can't remember what it said, but I do recall that it dismissed the possibility that Jimmie Rodgers picked it up from Black singers (despite Howlin' Wolf's claim that he taught Rodgers to yodel in the 1920s), and I think it would have been equally sceptical about Swiss cowboys. In fact it claimed that Rodgers picked the yodel up from Tyrolean Vaudeville acts who were apparently quite popular around then.

If I can find the damned thing, I'll have another read of it.