Pierce, T. J., (1959). MAREDUDD ap GRUFFYDD ap RHYS (1130 or 1131 - 1155), prince of Deheubarth. Dictionary of Welsh Biography. Retrieved 24 Jan 2020, from https://biography.wales/article/s-MARE-APG-1130
Pierce, T. J., (1959). RHYS ap GRUFFYDD (1132 - 1197), lord of Deheubarth, known in history as ‘Yr Arglwydd Rhys’ (‘The lord Rhys’).. Dictionary of Welsh Biography. Retrieved 24 Jan 2020, from https://biography.wales/article/s-RHYS-APG-1132