http://eu-chronicle.eu/2018/07/south-africas-self-made-water-crisis/?fbclid=IwAR0Y89mLrIGAOLoMfvMif19Ama8YutI-Lfg1gWgSxBuha7vkZSV8YT4hDlc   , 
https://www.dahl-madsen.dk/2015/08/vi-lever-paa-en-blaa-planet-med-masser-af-stof/?fbclid=IwAR3HF2_zeOGqKk3pvfzSQcoMQG20_XSrPwAuQAyXmhUIEWnx54mUV5sy4MQ   
https://www.dahl-madsen.dk/2015/08/vi-lever-paa-en-blaa-planet-med-masser-af-stof/