The standard text of the Summa theologiae is the editio Leonina – i.e. the edition prepared by members of the Dominican Order at the command of Pope Leo XIII. This is in vols. IV–VIII of S. Thomae Aquinatis opera omnia iussu Leonis XIII edita cura et studio Fratrum Praedicatorum (Rome, 1888–1948). The same text, with or without critical apparatus, can be consulted in numerous subsequent editions.
De regimine principum and De regimine Iudaeorum are in R. M. Spiazzi, S. Thomae Aquinatis opuscula philosophica (Turin and Rome, 1951). R. M. Spiazzi has also edited St Thomas's commentary on Aristotle's Politics, as In octo libros politicorum Aristotelis expositio (Turin and Rome, 1966).
Scripta super libros sententiarum is in vols. VI–VIII of S. Thomae opera omnia (25 vols., Parma, 1852–73; repr. New York, 1948–9).
The whole of the Summa theologiae is available in the following English translations:
Summa theologica, trans. Fathers of the English Dominican Province (2nd, rev. edn, 22 vols., London, 1912–36) (the 'Dominican Edition': see table of abbreviations).
Summa theologiae, trans. Thomas Gilby et al.(61 vols., London and New York, 1964–80) (the 'Blackfriars Edition'). This is a bilingual edition printed with the Leonine edition of the Latin text verso (without apparatus criticus) and the English translation recto.