In the ICEL translation of the Liturgy of the Hours, there’s a red note above the second reading, which seems to be a source citation. For example, for today’s reading by Saint Basil the Great, the note is:
(Cap. 15, 35-36: SC 17 bis, 364-370)
That’s just an example though, but what are these abbreviations? Is there a glossary or something that can tell me what all the abbreviations mean, and then find the source text for the Readings? Where does the Congregation for Divine Worship (*I assume they are the ones who created the original Latin Liturgia Horarum) draw these readings from and how do they decide that?