Hidden images in Atxurra Cave (Northern Spain): A new proposal for visibility analyses of Palaeolithic rock art in subterranean environments

1. Intxaurbe, I.
2. Rivero, O.
3. Medina-Alcaide, M.Á.
4. Arriolabengoa, M.
5. Ríos-Garaizar, J.
6. Salazar, S.
7. Ruiz-López, J.F.
8. Ortega-Martínez, P.
9. Garate, D.