Sources
Every timing rule in Rhythm and in the tools on this site cites one of these. Editions and translators are named. The rules are simplified for computation from classical electional doctrine; the full treatments are in the books, and the guides in the Library walk through them.
Classical reading list
Dorotheus of Sidon, Carmen Astrologicum, trans. Benjamin N. Dykes (Cazimi Press, 2017)
Hellenistic electional doctrine, especially Book V on beginnings.
Sahl ibn Bishr, On Elections, in Works of Sahl & Masha'allah, trans. Benjamin N. Dykes (Cazimi Press, 2008)
Arabic tradition on choosing moments for action.
Hephaistio of Thebes, Apotelesmatics Book III: On Inceptions, trans. Benjamin N. Dykes (Cazimi Press, 2013)
Late Hellenistic rules for beginnings and elections.
Vettius Valens, Anthologies, trans. Mark T. Riley (2010)
Personal significators and the Moon's relation to the natal chart.
William Lilly, Christian Astrology (London, 1647)
Renaissance electional practice, including void-of-course Moon.
Claudius Ptolemy, Tetrabiblos, trans. F. E. Robbins (Loeb Classical Library, 1940)
Foundational astrology of the Hellenistic world.
Picatrix, trans. Dan Attrell & David Porreca (Penn State University Press, 2019)
Planetary day rulerships and magical elections.
astronomy-engine (Don Cross), the open-source ephemeris the tools compute from
Positions of the Sun, Moon and planets, the moon phases, the solstices and equinoxes — computed for the minute, never looked up.