The Trikont disc which Stewie mentions above is the one I had in mind.
It shouldn't be too difficult to obtain. Apart from specialist dealers I have seen it in Virgin (Ex-Tower) in Piccadilly Circus so it isn't that obscure.

Re the query about yodelling getting to the US from Europe. Is this a fact? Is it not possible that it developed, from the field hollers or "arhoolies" of the black workers in the South where these calls were used as a means contact/identification between people some distance apart. I am a little unsure of this but I believe that in some parts of Africa similar means were used by forest dwellers.

Jimmie Rodgers visits the Carter Family, a prime example of a little going a long way.

Hoot (but don't yodel)