https://www.lse.ac.uk/granthaminstitute/publication/lionel_robbins2024/
https://theconversation.com/cual-es-el-material-mas-usado-del-mundo-y-el-que-menos-se-investiga-213576
https://www.ips-journal.eu/index.php?id=326&L=0&tx_news_pi1%5Bnews%5D=3904&tx_news_pi1%5Bcontroller%5D=News&tx_news_pi1%5Baction%5D=detail&utm_source=newsletter&utm_medium=email&utm_campaign=en_728_20191129&cHash=5d8677e040088390be92d9eb2a20fb32
https://www.dbresearch.de/PROD/RPS_DE-PROD/PROD0000000000523908/Deutschland%3A_Konjunktur_kurzgefasst.PDF