Brad Schaefer (Yale University). Heliacal Rising: Definitions, Calculations, and some Specific Cases (Essays from Archaeoastronomy & Ethnoastronomy News, the Quarterly Bulletin of the Center for Archaeoastronomy, Number 25.) [1]. Gearchiveerd op 19 oktober 2021.
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Brad Schaefer (Yale University). Heliacal Rising: Definitions, Calculations, and some Specific Cases (Essays from Archaeoastronomy & Ethnoastronomy News, the Quarterly Bulletin of the Center for Archaeoastronomy, Number 25.) [1]. Gearchiveerd op 19 oktober 2021.