Natural/Hand Horn Literature

I am looking for some natural horn literature and am having a bit of trouble finding some. Specifically I am looking for etude/study books. Any help would be appreciated.

James Fechter - SUNY Fredonia Student eventually going into Grad work in Musicology/Early Music

For me the best I've found was the Douprat "Horn Bible"
Method for Cor Alto and Cor Basse, can be found on the books section at: http://www.birdalone.com/

I came across this book in my findings too. Thanks for the information.

Please aks those boys:

http://www.koebl.de

They speak english, no problem to call them. You also can take a look to:

http://www.pizka.de

Very good is the Naturhornschule (Handhorn Methode) by Schantl. But I have no guess, where You can buy it, sorry.

I think the best introduction to natural/hand horn playing is Paul Austin's "A Modern Valve Horn Player's Guide to the Natural Horn"
This book is available at Birdalone.

Also anyone wishing to start with a great foundation to the technic and lore of the hand horn should consider Rick Seraphinoff's summer sessions at Indiana University.

Dear David, I am interested in this book.
But whats "birdalone"? Is it an (internet)shop or a editor?