Gloria I. Guzmán, Eduardo Aguilera, Roberto García-Ruiz, Eva Torremocha, David Soto-Fernández, Juan Infante-Amate, Manuel González de Molina, The agrarian metabolism as a tool for assessing agrarian sustainability, and its application to Spanish agriculture (1960-2008), Ecology and Society, Vol. 23, No. 1 (Mar 2018)