Here are the Summa references for the EF 4th Sunday of Advent, Christmas Day and Feast of Saint Stephen.
4th Sunday of Advent
EPISTLE (I Cor. 4:1-5)
"As ministers of Christ"
Holy Orders Suppl. Q.34
Hierarchy of powers and orders Suppl. Q.40, a.6; II-II Q.87, a.4, ad.2
"Here now it is required," etc.
Avoiding rash judgment II-II Q.60, a.2; a.3
"For I am not conscious to myself of anything, yet am I not hereby justified"
Can a man know he has grace? I-II Q.112, a.5
"Who both will bring to light the hidden things of darkness"
The book of life I Q.24
After resurrection will each one know all his sins? Suppl. Q.87, a.1
Will each one then read what is in the conscience of the other? Suppl. Q.87, a.2
GOSPEL (Luke 3:1-6)
"Preaching the baptism of Penance"
Why it became John to lead a severe life III Q.38, a.2, ad.2.
"For the remission of sins"
Did John's baptism confer grace? III Q.38, a.3
"And He came into all the country about the Jordan"
"And all flesh shall see the salvation of God"
The incarnation III Q.1
The manner of life of Christ III Q.40
Christmas Day
EPISTLE (Titus 2:11-15)
"The goodness and kindness of God our Savior hath appeared"
The infinite goodness of God I Q.6; III Q.1, a.2
"Not by the works of justice which we have done"
Can man merit eternal life? I-II Q.114, a.3
"But according to His mercy"
The mercy of God I Q.21
Whether eternal life is grace or mercy I-II Q.114, a.3, ad.2
How we are all born subject to sin I-II Q.81, a.1; a.3
"He saved us by the laver of regeneration"
Why Christ wished that grace be conferred on man through the sacraments. III Q.61
How Baptism is called the laver of regeneration III Q.66, a.1. ad.2
GOSPEL (Luke 2:1-14)
"Let us go over to Bethlehem"
Why did Christ wish to be born in Bethlehem? III Q.35, a.7
Why was not Christ born in Rome? III Q.35, a.7, ad.3
"They understood"
The gift of understanding II-II Q.8
The nativity of Christ III Q.35
The manifestation of the new-born Child III Q.36
"Glorifying and praising God"
Adoration of God II-II Q.84
Saint Stephen
EPISTLE (Acts 6:8-10; 7:54-59)
"Stephen, full of grace and fortitude"
The office of deacon Suppl. Q.37, a.3; a.4
The gift of fortitude II-II Q.123
Is plenitude of grace proper to Christ III Q.7, a.9; a.10
"Did great wonders and signs"
Miracles II-II Q.178
"Disputing with Stephen"
Should we dispute publicly with infidels II-II Q.10, a.7
"You have always resisted the Holy Ghost"
The sin against the Holy Ghost II-II Q.14
Was there contumely in St. Stephen's talk to Jews? II-II Q.72, a.2. ad.2
"Saw Jesus standing," etc.
How he saw Jesus standing when Christ had already risen and was sitting at right hand of the Father III Q.58, a.1, ad.3
"I see the heavens opened"
For whom is heaven open? III Q.49, a.5, ad.3
"Lord, lay not this to their charge"
The perfect love of our enemy II-II Q.25, a.8
GOSPEL (Matthew 23:34-39)
"Behold I send to you," etc. "And some of them you will put to death"
Ingratitude II-II Q,107
Martyrdom II-II Q.124
Confession of faith II-II Q.3
"That upon you may come all the just blood," etc.
Punishment of one for another's sin I-II Q.87, a.8
"How often would I hive gathered," etc.
Is God's will always fulfilled? I Q.19, a.6
Twofold will of God I Q.19, a.11
Cf. The Summa of St. Thomas Aquinas, Vol III, New York: Benziger, 1947, 3725-3726.