@article{allwood2011material,
  title = {Material efficiency: A white paper}
  author = {Allwood, Julian M. and Ashby, Michael F. and Gutowski, Timothy G. and Worrell, Ernst},
  journal = {Resources, Conservation and Recycling},
  url = {https://linkinghub.elsevier.com/retrieve/pii/S0921344910002405},
  year = {2011}
}