Melfou, K., A. Theocharopoulos, and E. Papanagiotou. “The Structure of Production in Greek Agriculture: Elasticities of Substitution and Derived Factor Price Elasticities”. SPOUDAI Journal of Economics and Business, vol. 59, no. 3-4, Dec. 2009, pp. 32-48, http://spoudai.org/index.php/journal/article/view/297.