Clim. past. Clim. past. Rogation ceremonies: A key to understanding past drought variability in northeastern Spain since 1650 Tejedor Ernesto De Luis Martín Universidad de Zaragoza Barriendos Mariano Cuadrat José María Universidad de Zaragoza Luterbacher Jürg Saz Miguel Ángel Universidad de Zaragoza 2019 research-article