@article {helbig2016extending,
	title = {Extending the geopolitical supply risk indicator: Application of life cycle sustainability assessment to the petrochemical supply chain of polyacrylonitrile-based carbon fibers},
	journal = {Journal of cleaner production},
	volume = {137},
	year = {2016},
	pages = {1170{\textendash}1178},
	publisher = {Elsevier},
	author = {Helbig, Christoph and Gemechu, Eskinder D and Pillain, Baptiste and Young, Steven B and Thorenz, Andrea and Tuma, Axel and Sonnemann, Guido}
}