292
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5. Nearly Half a Million Stars
47. https://local.strw.leidenuniv.nl/album1908/book_info.html.
48. Museum Boerhaave, www.museumboerhaave.nl/object/universeelinstrumentv10680/.
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50. www.saao.ac.za/about/history/.
51. Einstein’s Clocks, Poincaré’s Maps, Empires of Time by P. Galison, Norton, Londen;
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52. Digital Sky Survey (DSS): https://archive.stsci.edu/cgi-bin/dss_form.
53. Sloan Digital Sky Survey (SDSS): www.sdds.org/dr12.
6. Laboratory and Statistical Astronomy
54. From: Lijk Halfstok by Havank, Bruna, ISBN 9044930702 (1948), p.1:
55. From: Leven en werk van M.C. Escher, by F.H. Bool, J.R. Kist, J.L. Locher & F.
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57. www.eso.org/public/images/eso0932a/.
58. ESA/Hubble & Digitized Sky Survey 2. Davide De Martin (ESA/Hubble),
https://spacetelescope.org/images/heic1112f/.
59. National Optical Astronomy Observatories. Dale Cupp & Flynn
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60. www.astro.rug.nl/~vdkruit/Courses.html.
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References
46. https://kaarten.abc.ub.rug.nl/root/grs/krt-1868-grs/ and https://atlas1868.nl/
gr/groningen2.html.
5. Nearly Half a Million Stars
47. https://local.strw.leidenuniv.nl/album1908/book_info.html.
48. Museum Boerhaave, www.museumboerhaave.nl/object/universeelinstrumentv10680/.
49. Karl Ludwig von Littrow (1811–1877), in: Sitzungsberichte der MathematischNaturwissenschaftlichen Classe der Kaiserlichen Akademie der Wissenschaften,
Abtheilung II (Mathematik, Physik, Chemie, Mechanik, Meteorologie und
Astronomie), LII, 546-546 (1866), https://catalog.hathitrust.org/Record/
003086683.
50. www.saao.ac.za/about/history/.
51. Einstein’s Clocks, Poincaré’s Maps, Empires of Time by P. Galison, Norton, Londen;
ISBN 0-393-02001-0 (2003).
52. Digital Sky Survey (DSS): https://archive.stsci.edu/cgi-bin/dss_form.
53. Sloan Digital Sky Survey (SDSS): www.sdds.org/dr12.
6. Laboratory and Statistical Astronomy
54. From: Lijk Halfstok by Havank, Bruna, ISBN 9044930702 (1948), p.1:
55. From: Leven en werk van M.C. Escher, by F.H. Bool, J.R. Kist, J.L. Locher & F.
Wierda, Meulenhof, ISBN 9029011477 (1981), p.113.
56. The Hertzsprung Russell Diagram by Richard Powell, www.atlasoftheuniverse.com/
hr.html and https://en.wikipedia.org/wiki/File:HRDiagram.png.
57. www.eso.org/public/images/eso0932a/.
58. ESA/Hubble & Digitized Sky Survey 2. Davide De Martin (ESA/Hubble),
https://spacetelescope.org/images/heic1112f/.
59. National Optical Astronomy Observatories. Dale Cupp & Flynn
Haase/NOAO/AURA/NSF/.
www.noao.edu/outreach/aop/observers/n891.
html.
60. www.astro.rug.nl/~vdkruit/Courses.html.
61. Digital Sky Survey DSS2, Space Telescope Science Institute: https://stdatu.stsci.
edu/dss/.
62. Willem de Sitter: Einstein’s friend and opponent by J. Guichelaar, Springer biographies, Springer Publishers, ISBN978-3-319-98336-3 (20018).
63. Resumé van K’s onderzoekingen naar de ‘Structure of the Universe’, 12 April 1907,
www.astro.rug.nl/JCKapteyn/byJCK.html.
64. The International Astronomical Union Constellations: www.iau.org/public/
themes/constellations/.