Measuring the Intangibles: A Metrics for the Economic Complexity of Countries and Products Cristelli, Matthieu ; Gabrielli, Andrea ; Tacchella, Andrea ; Caldarelli, Guido ; Pietronero, Luciano Abstract Publication: PLoS ONE Pub Date: August 2013 DOI: 10.1371/journal.pone.0070726 Bibcode: 2013PLoSO...870726C