Analysis of information sources in references of the Wikipedia article "Titular see" in English language version.
Canon 348: Episcopi titulares nullam possunt exercere potestatem in sua dioecesi, cuius nec possessionem capiunt. Decet ex caritate, citra tamen obligationem, ut aliquando Missae sacrificium pro sua dioecesi applicent.
Canon 376: Bishops to whom the care of some diocese is entrusted are called diocesan; others are called titular.