OsterbrockD. E., James E. Keeler, pioneer American astrophysicist, and the early development of American astrophysics (Cambridge, 1984).
2.
WrightW. H., “The wave-lengths of the nebular lines and general observations of the spectra of the gaseous nebulae”, Publications of the Lick Observatory (hereafter: PLO), xiii (1918), 193–268.
3.
CampbellW. W.MooreJ. H., “The spectrographic velocities of the bright-line nebulae”, PLO, xiii (1918), 75–183.
4.
CurtisH. D., “The planetary nebulae”, PLO, xiii (1918), 55–74.
5.
HubbleE., “A general study of diffuse galactic nebulae”, Astrophysical journal (hereafter: ApJ), lvi (1922), 162–99; “The source of luminosity in galactic nebulae”, ApJ, lvi (1922), 400–38.
6.
SlipherV. M., “On the spectrum of the nebula in the Pleiades”, Lowell Observatory bulletin (hereafter: LOB), ii (1913), 26–27; “On the spectrum of the nebula about Rho Ophiuchi”, LOB, ii (1916), 155–6.
7.
RussellH. N., “Dark nebulae”, Proceedings of the National Academy of Sciences, viii (1922), 115–18.
8.
RedmanR. O., “Anniversary meeting of the Royal Astronomical Society 1961 February 10”, Observatory, lxxxi (1961), 45–47, and PlaskettH. H., “Herman Zanstra”, Quarterly journal of the Royal Astronomical Society, xv (1974), 59–66, are the two main biographical sources for Zanstra, used throughout this paper, supplemented by his very detailed entries in successive editions of J. C. Poggendorf, Biographische-Literarisches Handwörterbuch zur Geschichte der exacten Wissenschaften.
9.
ZanstraH., “Die Relativierung der Bewegung mit Hilfe der Hypothese von A. Föppl”, Annalen der Physik, lxx (1923), 153–60.
10.
“Ph.D. Degrees, School of Physics, University of Minnesota”, undated [c.1928], University of Minnesota, School of Physics Records (hereafter: UM). Zanstra was the sixteenth Ph.D. in physics at Minnesota, and the ninth of them to do his thesis under Swann's supervision. Their first Ph.D. in physics there had been granted in 1906.
11.
Zanstra, “NRC Fellowships in Physics and Astronomy” [typed application], 17 Mar. 1923; “Personal history record submitted in connection with application for a Fellowship”, 17 Mar. 1923, Rockefeller Archives Center, Tarrytown, NY (hereafter: RAC); “A study of relative motion in connection with classical mechanics”, Physical review, xxiii (1924), 528–45.
12.
“Herman Zanstra” [NRC record card], 26 June [19]24; W. E. Tisdale to W. Lund, 14 Jan. 1925; H. Zanstra, “Report on the progress of the work carried out”, 20 Feb. 1925; “Extract from Dr. Hanson's Log”, Zürich, 12 Dec. 1931; RAC.
13.
Zanstra to A. Trowbridge, 3 Mar., 7 Apr., 15 Apr. 1925; Zanstra to Tisdale, 14 Apr., 12 May 1925; Trowbridge, “From [a] letter [regarding Zanstra]”, 14 Jan. 1926; RAC.
14.
Zanstra, “An application of quantum theory to the emission of light by diffuse nebulae” (18-page typed draft manuscript including an abstract and one figure), [3] July 1925, RAC.
15.
Zanstra to Trowbridge, 3 July, 20 Aug. 1925; NRC Research Fellowship Board in Physics, Chemistry, and Mathematics minutes, 23 Apr., 19 June 1925, National Academy of Sciences Archives, Washington.
16.
ZanstraH., “An application of the quantum theory to the luminosity of diffuse nebulae”. Physical review, xxvii (1926), 644.
17.
ZanstraH., “An application of the quantum theory to the luminosity of diffuse nebulae”, ApJ, lxv (1927), 50–70.
18.
Zanstra to D. Thomson, 27 May 1927, F. H. Padelford to R. G. Aitken, 3 Aug. 1928, University of Washington Archives, Seattle (hereafter: UW).
19.
BabcockH. W., “Ira Sprague Bowen: 1898–1973”, Biographical memoirs of the National Academy of Sciences (hereafter: BMNAS), lviii (1982), 83–119.
20.
ZanstraH., “Temperatures of stars in planetary nebulae”, Nature, cxxi (1928), 791–2.
21.
ZanstraH., “Luminosity of planetary nebulae and stellar temperatures”, Publications of the Dominion Astrophysical Observatory, iv (1931), 209–60.
22.
“Extract from W. E. Tisdale's log”, London, 5 Feb. 1930, RAC.
23.
“Bericht über die Versammlung der Astronomische Gesellschaft zu Heidelberg, 1928 Juli, 18–21”, Vierteljahrschrift der Astronomischer Gesellschaft, lxiii (1928), 246–71; SchorrR., “Hamburg-Bergedorf Jahresbericht für 1930”, ibid., lxvi (1931), 164–83.
24.
ZanstraH., “Untersuchungen über planitarischen Nebel. I. Der Leuchtprozess planetarischer Nebel und die Temperatur der Zentralsterne”, Zeitschrift für Astrophysik, ii (1931), 1–29.
25.
ZanstraH., “Untersuchungen über planitarischen Nebel. II. Parallaxen, Expansion der Nebelhülle”, Zeitschrift für Astrophysik, ii (1931), 329–44.
26.
ZanstraH., “An expansion hypothesis for planetary nebulae”, Monthly notices of the Royal Astronomical Society, xciii (1932), 131–49.
27.
MenzelD. H., “Physical processes in gaseous nebulae”, Publications of the Astronomical Society of the Pacific (hereafter: PASP), xliii (1931), 334–9.
Aitken to Menzel, 31 Mar. 1926, Mary Lea Shane Archives of the Lick Observatory, University Library, University of California, Santa Cruz (hereafter: SLO).
31.
MenzelD. H., “The planetary nebulae”, PASP, xxxviii (1926), 295–312.
MenzelD. H., “The atmosphere of Mars”, ApJ, lxiii (1926), 48–59.
34.
ShaneC. D., “William Hammond Wright”, BMNAS, l (1979), 377–96.
35.
See ref. 16.
36.
OsterbrockD. E.GustafsonJ. R.UnruhW. J. S., Eye on the sky: Lick Observatory's first century (Berkeley and Los Angeles, 1988).
37.
Zanstra to Aitken, 19 Aug. 1935, SLO.
38.
“From Dr. W. E. Tisdale's diary”, Amsterdam, 10 Mar. 1937, RAC; Zanstra to J. W. Buchta, 10 Apr., 17 July 1941, UM; O. Struve to H. Shapley, 11 Aug. 1941, Yerkes Observatory Archives, Williams Bay, WI.
39.
MenzelD. H., “Concluding remarks”, Mémoires de la Société Royale de Liège, v (1973), 19–30.
40.
W. Baade to Zanstra, 16 Oct. 1950, Mount Wilson Observatory Collection, Huntington Library, San Marino, CA.
41.
Menzel to H. N. Russell or R. S. Dugan, 22 Jan. 1931 (two telegrams), Menzel to Russell, 23 Jan., 3 Feb. 1931, undated [c. 1 May 1932]; Menzel to Dugan, 24 Jan. 1931; Henry Norris Russell Papers, Special Collections, Princeton University Library (PU).
