Scale-Invariance of Normalized Yearly Mean Grain Yield Anomaly Series. - Ricardo David Valdez-Cepeda; Olivia Delgadillo-Ruiz; Rafael Magallanes-Quintanar; Gerardo Miramontes de León; José Luis García-Hernández; Agustín Enciso-Muñoz; Blanca Mendoza (Adv. Complex Syst., 2007)