A whole CD of it:
http://www.uddatoner.com/huvuddokument.html

Another sample:
http://www.links.net/vita/trip/scand/sweden/muzik/

More:
http://aufildutemps.typepad.com/au_fil_du_temps/2006/05/chants_des_patr.html

Article by Rosenberg:
http://www.isvroma.org/pecus/rosenberg.pdf

Very substantial article by Anna Ivarsdotter:
http://www.isvroma.org/pecus/ivarsdotter.pdf