The Adolfo Stahl lectures in astronomy, delivered in San Francisco, California, in 1916-17 and 1917-18, under the auspices of the Astronomical Society of the Pacific (1919)
Astronomical Society of the Pacific, Aitken, Robert Grant, 1864-1951 · San Francisco Stanford University Press · leaf 170
Fig. 1—The Spiral Nebula, N. G. C. 7479. Fig. 2—The Spiral Nebula. Messier 51.
Astronomy
Internet Archive · Gerstein Library, University of Toronto · Public Domain Mark 1.0. Free to use for anything.
