Hidden images in Atxurra Cave (Northern Spain): a new proposal for visibility analyses of Palaeolithic rock art in subterranean environments - Intxaurbe Alberdi, Iñaki; Rivero, Olivia; Medina-Alcaide, María Ángeles; Arriolabengoa, Martín; Ríos Garaizar, Joseba; Salazar Cañarte, Sergio; Ruiz López, Juan Francisco; Ortega-Martínez, Paula; Gárate Maidagán, Diego (2020)