Bibliographical references Abate G. T., Francesconi G. N., y Getnet K. (2014) Impact of agricultural cooperatives on smallholders technical efficiency: Empirical evidence from Ethiopia. Annals of Public and Cooperative Economics, 85, pp. 257–286. Adelaja, A. O. (1992) Material Productivity in Food Manufacturing. American Journal of Agricultural Economics, 74(1), pp. 177-85. Ahn S. C., Brada J. C., y Mendez J. A. (2012) Effort, technology and the efficiency of agricultural cooperatives. Journal of Development Studies, 48, pp. 1601–1616. Andersen, P., y Petersen, N. C. (1993) A procedure for ranking efficient units in data envelopment analysis. Management Science, 39(10), pp. 1261–1264. doi:10.1287/mnsc.39.10.1261. Arcas, N., García G., y Melia, E. (2014) El tamaño de las cooperativas agroalimentarias como factor de competitividad. En: Arcas N. y Hernández, M. (coord. y dir.) Tamaño y competitividad. Experiencias de crecimiento en las cooperativas agroalimentarias españolas. Ed. Cajamar Caja Rural. Arcas, N., García, D. y Sánchez, J.L. (2019) Diagnóstico económico-financiero de las cooperativas agroalimentarias en España (2015-2017). Ed. Cajamar Caja Rural. Banker, R.D., Charnes, A. y Cooper, W.W. (1984) Some models for estimating technical and scale inefficiencies in data envelopment analysis. Management Science, Vol. 30 No. 9, pp. 1078-1092. Brandano M.G., Detotto, C., y Vannini, M. (2019) Comparative efficiency of agricultural cooperatives and conventional firms in a sample of quasi-twin companies. Annals of Public and Cooperative Economics, 90(1), pp. 53-76, https://doi.org/10.1111/apce.12220. Charnes, A., Cooper, W. W., y Rhodes, E. (1978) Measuring the efficiency of decision making units. European Journal of Operational Research, 2(6), pp. 429–444. doi:10.1016/0377-2217(78)90138-8. Christensen, L.R. (1975) Concepts and measurement of agricultural productivity. American Journal of Agricultural Economics, 75(5), pp. 910-915. Chung, Y. H., Färe, R., y Grosskopf, S. (1997) Productivity and undesirable outputs: A directional distance function approach. Journal of Environmental Management, 51(3), pp. 229–240. doi:10.1006/jema.1997.0146. Cos, P., Aldaz, N., Escardíbul, B., Millán, J.S. y Moltó, M. (2019) Indicadors de competitivitat al cooperativisme agràri a Catalunya. Editorial UOC. Barcelona. Emrouznejad A. y G. Yang (2018) A survey and analysis of the first 40 years of scholarly literature in DEA: 1978–2016. Socio-Economic Planning Sciences, 61(1), pp. 1-5. http://dx.doi.org/10.1016/j.seps.2017.01.008. Farrell, M.J. (1957) The Measurement of Productive Efficiency. Journal of the Royal Statistical Society, 120, pp. 253-290. https://doi.org/10.2307/2343100. Galdeano E. (2006) Productivity and efficiency analysis of horticultural co-operatives. Spanish Journal of Agricultural Research, 4(3), pp. 191-201. Goerlich, F.J. y Orts, V. (1996) Economías de escala, externalidades y atesoramiento de trabajo en la industria española, 1964-1989. Revista de Economía Aplicada, 11(vol. 4), pp. 151-166. Grashuis, J., y Su, Y. (2019) A review of the empirical literature on farmer cooperatives: Performance, ownership and governance, finance and member attitude. Annals of Public and Cooperative Economics 90(1), pp. 77–102, https://doi.org/10.1111/apce.12205. Gumbau-Albert, M. y Maudos, J. (1996) Eficiencia productiva sectorial en las regiones españolas: Una aproximación frontera. Revista Española de Economía, 13(2), pp. 239-60. Juliá, J. F., Meliá, E., García, G. y Gallego, P. L. (2010) Los factores de competitividad de las cooperativas líderes del sector agroalimentario europeo. Acciones a emprender por las cooperativas agrarias españolas. Fundación Cajamar, Almería. Liu J.S., Lu, L.Y.Y., Lu, W.-M. y Lin, B. J.Y. (2013) A survey of DEA applications, Omega 41(5), pp. 893-902. Martínez E., Díaz R., Navarro M., y Ravelo T. (1999) A study of the efficiency of Spanish port authorities using data envelopment analysis. International Journal of Transport Economics 2, pp. 237-253. Martínez-Victoria, M.C., Maté Sánchez-Val, M., y Arcas-Lario, N. (2018) Spatial determinants of productivity growth on agri-food Spanish firms: A comparison between co-operatives and investor-owned firms. Agricultural Economics, 49(2), pp. 213-223. Millán, J.A. y Aldaz, N. (2004) Efficiency and Technical Change in Intertemporal Intersectoral DEA. Journal of Productivity Analysis, 21(1), pp. 7-23. https://doi.org/10.1111/agec.12410. OSCAE. (2019) El cooperativismo agroalimentario español Informe socioeconómico 2018. MAPA Pastor JT, Ruiz JL y Sirvent I. (1999) An enhanced DEA Russell graph efficiency measure. European Journal of Operational Research 115, pp. 596-607 Pedraja, F., Ramajo, J. y Salinas, J. (1999) Eficiencia productiva del sector industrial español: un análisis espacial y sectorial. Papeles de Economía Española, 82, pp. 51-68. Ray, S.C. (2020) Data Envelopment Analysis: A Nonparametric Method of Production Analysis. En S. C. Ray, R. Chambers y S. Kumbhakar (eds) Handbook of Production Economics, Springer (en prensa) https://doi.org/10.1007/978-981-10-3450-3_24-1. Tone K. (2001) A slacks-based measure of efficiency in data envelopment analysis. European Journal of Operational Research, 130, pp. 498-509.