Nussbaumer, Harry (2013). 'Slipher's redshifts as support for de Sitter's model and the discovery of the dynamic universe' In Origins of the Expanding Universe: 1912–1932. Astronomical Society of the Pacific. pp. 25–38.Physics ArXiv preprint
O'Raifeartaigh, Cormac (2013). The Contribution of V.M. Slipher to the discovery of the expanding universe in 'Origins of the Expanding Universe'. Astronomical Society of the Pacific. pp. 49–62.Physics ArXiv preprint
Slipher, V.M. (1917). "Radial velocity observations of spiral nebulae". The Observatory. 40: 304–306. Bibcode:1917Obs....40..304S.
Slipher, Vesto (1917). "Nebulae". Proceedings of the American Philosophical Society. 56: 403–409. Bibcode:1917PAPhS..56..403S.
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Slipher first reports on the making the first Doppler measurement on September 17, 1912 in The radial velocity of the Andromeda Nebula in the inaugural volume of the Lowell Observatory Bulletin, pp. 2.56–2.57. In his report Slipher writes: "The magnitude of this velocity, which is the greatest hitherto observed, raises the question whether the velocity-like displacement might not be due to some other cause, but I believe we have at present no other interpretation for it." Three years later, Slipher wrote a review in the journal Popular Astronomy, Vol. 23, pp. 21–24 Spectrographic Observations of Nebulae, in which he states, "The early discovery that the great Andromeda spiral had the quite exceptional velocity of -300 km(/s) showed the means then available, capable of investigating not only the spectra of the spirals but their velocities as well." Slipher reported the velocities for 15 spiral nebula spread across the entire celestial sphere, all but three having observable "positive" (that is recessional) velocities.
