Baptism and Confirmation by 
For specific English translations like the three listed below – ask your reference librarians for help:
QDSC: Quaestio disputata de spiritualibus creaturis = Disputed Question on Created Spirits
SCG: Summa contra gentiles = On the Truth of the Catholic Faith
DSS: De Substantiis Separatis = Treastise on Separate Substances
This sample search is for the New Advent Online Version of the Summa – see keywords to use below.
Go to WorlCat First Search at this hyperlink:
WorldCat (First Search version)
In WorldCat
1. Start on the search screen and try these three keywords
Keyword: Advent
Author: Aquinas
Title: Summa
2. Choose the top catalog record.
3. Click on Cite This Item hyperlink in catalog record
4. Choose the citation that conforms to your assigned style manual. Double check with your style manual to make sure this is correct.
5. Wait - there's more: Now go o to the box below for internal citation examples.
6. Choose the initial citation that conforms to your assigned style manual.
a. When citing medieval authors, give the “internal reference,” not only the “external one.” For example, when citing from Aquinas’s De malo, do not merely indicate the page number of your edition or translation, but also the reference to question and article.
b. On the other hand, works of medieval authors, other than Aquinas’s Summa theologiae, must be cited with the “external reference” in addition to the “internal reference,” i.e., with page references to the translation or edition used. (When referring to the Latin text, use the Leonine edition wherever it is available.) In other words, only the Summa theologiae may be cited with only the “internal citation,” such as ST 1a2ae.8.1. (There is no uniform method of citing medieval texts. A variety of methods are acceptable, such as: ST I–II, q. 8, a. 1.)
c. This website is also helpful:
http://souldevice.wordpress.com/2010/09/21/citing-thomas-aquinas%E2%80%99s-summa-theologiae/