It may be difficult to find, but there is an excellent CD of old-time performers on the German Trikont label: Various Artists 'American Yodeling 1911-1946' Trikont US-0246-2. The highlight for me is a stunning side by the DeZurich Sisters titled 'The Arizona Yodeler'. The compilation also includes Monroe's rendition of 'Mule Skinner Blues' mentioned above.

--Stewie.