Rullan-Silva, C.D., A.E. Olthoff, J.A. Delgado de la Mata, and J.A. Pajares-Alonso. 2013. “Remote Monitoring of Forest Insect Defoliation -A Review-”. Forest Systems 22 (3), 377-91. https://doi.org/10.5424/fs/2013223-04417.