@article{wei-qiang2015in-use,
  title = {In-use product stocks link manufactured capital to natural capital}
  author = {Wei-Qiang Chen and T.E. Graedal},
  journal = {Proceedings of the National Academy of Sciences of the United States of America (PNAS)},
  doi = {10.1073/pnas.1406866112},
  year = {2015}
}