I hope someone can point me in the right direction. I'm trying to find out what Church documents guided the Liturgical Year before Vatican II?

I know that the 1969 Calendar reform was guided by the Vatican II document Sacrosanctum Concilium, and then General Reform of the Liturgical Calendar was the issued document that shaped the General Roman Calendar.

I have loads of books and missals that all try to explain and illuminate the General Roman Calendar, the Liturgical Calendar, the cycles of the liturgical year, the feasts, etc., but I can't find references to the actual official Church teachings or documents that set up and explained the calendar before 1969.

I'm sure most are still in Latin, but any help in this would be greatly appreciated! Thanks in advance.