SECOND VATICAN COUNCIL, DECREE CHRISTUS DOMINUS, n. 23, 3), 28-X-1965, AAS 58 (1966) 579-597
Finally, in order that the ministry of salvation be more effectively carried out in each diocese, it should be considered a general rule that each diocese have clergy, in number and qualifications at least sufficient, for the proper care of the people of God; also, there should be no lack of the offices, institutions and organizations which are proper to the particular church and which experience has shown necessary for its efficient government and apostolate; finally, resources for the support of personnel and institutions should be at hand or at least prudently foreseen in prospect.
For this same purpose, where there are faithful of a different rite, the diocesan bishop should provide for their spiritual needs either through priests or parishes of that rite or through an episcopal vicar endowed with the necessary faculties. Wherever it is fitting, the last named should also have episcopal rank. Otherwise the Ordinary himself may perform the office of an Ordinary of different rites. If for certain reasons, these prescriptions are not applicable in the judgment of the Apostolic See, then a proper hierarchy for the different rites is to be established.(16)
(16): cf. Second Vatican Council, Decree on Eastern Catholic Churches, Nov. 21, 1964, no. 4: A.A.S. 57 (1965) p. 77.