Pertanyaan ini merujuk pada Grundfrage der Metaphysik Heidegger, Martin (2000). Einführung in die Metaphysik, trans. Gregory Field & Richard Polt. Yale University Press.Hapus pranala luar di parameter |title= (bantuan)
Aquinas, Thomas; Schultz, Janice L.; Synan, Edward A.; Boethius (2001). An exposition of the On the hebdomads of Boethius : Expositio libri Boetii De ebdomadibus. Thomas Aquinas in Translation. V (original scripture). Catholic University of America Press.