Since 1875, Frederick Field’s edition of Origen’s Hexapla has been the standard reference for the work. A new edition is in preparation under the auspices of the Hexapla Project. But, for the present, Field’s work remains an invaluable resource. His two-volume edition is available via Internet Archive.
The second English edition of Wilhelm Gesenius’s Hebrew Grammar (ed., E. Kautzsch, trans. A. Cowley) is based on the 28th edition of the German text. I recently came across a curiosity in the English text that made me want to have a look at the German behind it. Thankfully, Internet Archive has several versions of Gesenius-Kautzsch, and at least one of these is of the grammar’s 28th edition.
A major critical edition of the Old Latin is underway under the auspices of the Vetus Latina Institute. Some volumes have already been released. But, others are still forthcoming.
Meanwhile, the only complete edition of the Old Latin remains that published by Pierre Sabatier (Reims: 1739–1749; see Würthwein, Text of the Old Testament, 147). A later version of this edition, with some volumes reissued in later years, seems to have had three volumes, all of which are available on Internet Archive:
For reader’s convenience, the bottom of each page indicates the portion of the biblical text covered in that page’s facsimile, with hand-written notes over the facsimiles to indicate the starts of chapters.
The quality of the scan seems to be quite good. Below is an excerpt from Deut 30:2 (on pg. 248) showing the asterisks and metobelus used to mark what seems to be a revision toward the text represented in the MT.
It takes some digging, but Internet Archive appears to have the entire edition of Thomas Aquinas’s Summa Theologica translated by the Fathers of the English Dominican Province (London: Burns, Oats, and Washbourne, 1913–1929). Links to the individual volumes are below. Comments are certainly welcome if anyone notices a volume(s) that I’ve missed out.
The Internet Archive has PDF scans openly available for each of the first three volumes of Hermann Strack and Paul Billerbeck’s Kommentar zum Neuen Testament aus Talmud und Midrasch, 6 vols. (München: Beck, 1922–1961):1