In Masses celebrated without a congregation, any Catholic priest of the Latin rite, whether secular or regular, may use either the Roman Missal published in 1962 by Blessed Pope John XXIII or the Roman Missal promulgated in 1970 by Pope Paul VI, and may do so on any day, with the exception of the Easter Triduum.
Itaque confestim dimissis nuntiis ad Ceutrones, Grudios, Levacos, Pleumoxios, Geidumnos, qui omnes sub eorum imperio sunt, quam maximas manus possunt cogunt et de improviso ad Ciceronis hiberna advolant nondum ad eum fama de Tituri morte perlata.vatican.va vatican.va