F. Llana, Daniel, Guillermo Íñiguez-González, M. Rafael Díez, and Francisco Arriaga. 2020. “Nondestructive Testing Used on Timber in Spain: A Literature Review”. Maderas-Cienc Tecnol 22 (2):133-56. https://revistas.ubiobio.cl/index.php/MCT/article/view/3929.