Graduate Theology

Selected and edited by Henry Bettenson and Chris Maunder.
4th edition. Oxford: Oxford University Press, 2011.
A standard collection of excerpts from the primary sources most frequently referred to in theological study: from antiquity to the modern period and including both Catholic and Protestant documents.
For print version locations, see the UofT Library Catalogue.

Edited by William A. Jurgens.
Collegeville, MN: Liturgical Press, 1970-1979. 3 volumes.
English-language translations of the 2388 most important patristic passages needed for theological study each preceded by a brief explanation. Arranged in chronological order using the passage numbers used by M.J. Rouët de Journel in his Enchidion patristicum (where the Greek or Latin-language originals of the selections can be found). There is a detailed theological index which enables the user to find all the selections on a particular topic (e.g. the Holy Spirit).
All three volumes are available online on the Internet Archive, a trusted source, but one for which it is necessary to create a free account and login:
volume 1,
volume 2,
volume 3.

Thomas Aquinas.
London: Blackfriars, 1964-1976. 61 volumes.
Saint Thomas' Summa theologiae is the principal doctrinal synthesis of Catholic theology. The 1964 edition by the English Dominicans includes the Latin text and an English-language translation on facing pages; each volume includes a subject index and a useful glossary of theological terms.
Some volumes of the 1964 edition are available online on the Internet Archive, a trusted source, but one for which it is necessary to create a free account and login:
volume 1 (1a 1-13),
volume 7 (1a 33-43),
volume 14 (1a2ae 103-109),
volume 15 (1a 2ae 110-119),
volume 27 (1a2ae 86-89),
volume 31 (2a2ae 1-7),
volume 33 (2a2ae 17-22),
volume 38 (2a 2ae 63-79),
volume 40 (2a2ae 92-100),
volume 41 (2a 2ae 101-122),
volume 44 (2a 2ae 155-170),
volume 45 (2a 2ae 171-178),
volume 47 (2a 2ae 183-189),
volume 48 (3a 1-6),
volume 49 (3a 7-15),
volume 51 (3a 27-30),
volume 52 (3a 31-37),
volume 51 (3a 38-45),
volume 56 (3a 60-65),
volume 59 (3a 79-83).
There are several other English translations available online including the 1920 version by the English Dominicans and a contemporary version by Alfred J. Freddoso.