Hjelme, Sidsel; Ryvik, Hugo (26 February 2007). "Får møkkajobbene gjort". prosessindustrien.no (in Norwegian). Archived from the original on 2011-07-24.
Hjelme, Sidsel; Ryvik, Hugo (26 February 2007). "Får møkkajobbene gjort". prosessindustrien.no (in Norwegian). Archived from the original on 2011-07-24.