Catholic Encyclopedia: St. Ninian
Also known as Ninias, Ninus, Dinan, Ringan, or Ringen. Bishop and confessor, died about 432. British by birth, St. Ninian evangelized the southern Picts in Scotland.
Catholic Online: St. Ninian
Biographical sketch relates part of what St. Aelred says of Ninian, but not the much earlier information from the Venerable Bede.
Firth's Celtic Scotland: St Ninian
Biographical of the first Apostle of the Picts, with details of the extent of his ministry and legacy.
The Life of St. Ninian
By St. Aelred of Rievaulx. Written in Middle English, then translated into Latin. Does not say who translated this into Elizabethan English.
Whithorn Trust: Saint Ninian Sites
Locations throughout Scotland traditionally associated with Ninan or his disciples.