Heliumdokumentasjon
U.S. Geological Survey, Mineral Commodity Summaries, January 2018

Heliumdokumentasjon for flere år: https://minerals.usgs.gov/minerals/pubs/commodity/helium/

Artikkel i Daily Mail: Om stort funn av helium i Tanzania.

Artikkel Geological Society in London “Helium – Hero or Houdini?”

Artikkel i Forbes “We’re really not about to run out of helium…”

PEBA Media Release 16/01/2018

Mass Latex Balloon Releases and the Potential Effects on Wildlife
Stephan Irwin – Clemson Uni – 2012

Inhaling Helium Can Be Deadly
Medscape – Deborah Brauser – 2012

Origins, transport and accumulation of Helium 
The Geological Society

Species Profile – Rubber Tree
Rainforest Alliance