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Jacobs 1978, pp. 183. Jacobs, Nicholas (1978). "The German Social Democratic Party School in Berlin, 1906-1914". History Workshop History Workshop. 5 (5): 179–187. doi:10.1093/hwj/5.1.179. JSTOR4288169.
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van den Heuvel 2019, pp. 29. Pannekoek first published his suspicions on the variability of Polaris as a footnote in 1906 (Pannekoek 1906, p. 148). His observations were published in 1913 (Pannekoek 1913) van den Heuvel, Edward (2019). "Anton Pannekoek's Astronomy in Relation to his Political Activities, and the Founding of the Astronomical Institute of the University of Amsterdam". In Tai, Chaokang; van der Streen, Bart; van Dongen, Jeroen (eds.). Anton Pannekoek: Ways of Viewing Science and Society. Amsterdam: Amsterdam University Press. pp. 9–23. doi:10.2307/j.ctvp7d57c.4. ISBN9789462984349. Pannekoek, Anton (1906). "The luminosity of stars of different types of spectrum". Proceedings of the Section of Science, Koninklijke Akademie van Wetenschappen. 9 (2): 1192–1199. Bibcode:1906KNAB....9..134P – via KNAW Digital Library. Pannekoek, Anton (1913). "The variability of the Pole-star". Proceedings of the Section of Science, Koninklijke Akademie van Wetenschappen. 15 (1): 134–148 – via KNAW Digital Library.
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Smith 2019, pp. 119–122, Tai 2021, pp. 137–144. Smith, Robert W. (2019). "Astronomy in the Time of Pannekoek and Pannekoek as an Astronomer of his Times". In Tai, Chaokang; van der Streen, Bart; van Dongen, Jeroen (eds.). Anton Pannekoek: Ways of Viewing Science and Society. Amsterdam: Amsterdam University Press. pp. 109–136. doi:10.2307/j.ctvp7d57c.8. ISBN9789462984349. Tai, Chaokang (2021). Anton Pannekoek, Marxist Astronomer: Photography, Epistemic Virtues, and Political Philosophy in Early-Twentieth Century Astronomy (Ph.D. Thesis). University of Amsterdam. hdl:11245.1/ffd11908-9018-492c-8805-952387d964fc.
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Voerman 2019, pp. 61–68. Voerman, Gerrit (2019). "Anton Pannekoek: A 'Principled Theorist'". In Tai, Chaokang; van der Streen, Bart; van Dongen, Jeroen (eds.). Anton Pannekoek: Ways of Viewing Science and Society. Amsterdam: Amsterdam University Press. pp. 51–74. doi:10.2307/j.ctvp7d57c.5. ISBN9789462984349.
Smith 2019, pp. 119–122, Tai 2021, pp. 137–144. Smith, Robert W. (2019). "Astronomy in the Time of Pannekoek and Pannekoek as an Astronomer of his Times". In Tai, Chaokang; van der Streen, Bart; van Dongen, Jeroen (eds.). Anton Pannekoek: Ways of Viewing Science and Society. Amsterdam: Amsterdam University Press. pp. 109–136. doi:10.2307/j.ctvp7d57c.8. ISBN9789462984349. Tai, Chaokang (2021). Anton Pannekoek, Marxist Astronomer: Photography, Epistemic Virtues, and Political Philosophy in Early-Twentieth Century Astronomy (Ph.D. Thesis). University of Amsterdam. hdl:11245.1/ffd11908-9018-492c-8805-952387d964fc.
Tai 2021, pp. 151–166. Tai, Chaokang (2021). Anton Pannekoek, Marxist Astronomer: Photography, Epistemic Virtues, and Political Philosophy in Early-Twentieth Century Astronomy (Ph.D. Thesis). University of Amsterdam. hdl:11245.1/ffd11908-9018-492c-8805-952387d964fc.
Tai 2021, pp. 166–175. Tai, Chaokang (2021). Anton Pannekoek, Marxist Astronomer: Photography, Epistemic Virtues, and Political Philosophy in Early-Twentieth Century Astronomy (Ph.D. Thesis). University of Amsterdam. hdl:11245.1/ffd11908-9018-492c-8805-952387d964fc.
Tai 2021, pp. 148–150. Tai, Chaokang (2021). Anton Pannekoek, Marxist Astronomer: Photography, Epistemic Virtues, and Political Philosophy in Early-Twentieth Century Astronomy (Ph.D. Thesis). University of Amsterdam. hdl:11245.1/ffd11908-9018-492c-8805-952387d964fc.
Tai 2021, pp. 230. Tai, Chaokang (2021). Anton Pannekoek, Marxist Astronomer: Photography, Epistemic Virtues, and Political Philosophy in Early-Twentieth Century Astronomy (Ph.D. Thesis). University of Amsterdam. hdl:11245.1/ffd11908-9018-492c-8805-952387d964fc.
van den Heuvel 2019, pp. 29. Pannekoek first published his suspicions on the variability of Polaris as a footnote in 1906 (Pannekoek 1906, p. 148). His observations were published in 1913 (Pannekoek 1913) van den Heuvel, Edward (2019). "Anton Pannekoek's Astronomy in Relation to his Political Activities, and the Founding of the Astronomical Institute of the University of Amsterdam". In Tai, Chaokang; van der Streen, Bart; van Dongen, Jeroen (eds.). Anton Pannekoek: Ways of Viewing Science and Society. Amsterdam: Amsterdam University Press. pp. 9–23. doi:10.2307/j.ctvp7d57c.4. ISBN9789462984349. Pannekoek, Anton (1906). "The luminosity of stars of different types of spectrum". Proceedings of the Section of Science, Koninklijke Akademie van Wetenschappen. 9 (2): 1192–1199. Bibcode:1906KNAB....9..134P – via KNAW Digital Library. Pannekoek, Anton (1913). "The variability of the Pole-star". Proceedings of the Section of Science, Koninklijke Akademie van Wetenschappen. 15 (1): 134–148 – via KNAW Digital Library.
Jacobs 1978, pp. 183. Jacobs, Nicholas (1978). "The German Social Democratic Party School in Berlin, 1906-1914". History Workshop History Workshop. 5 (5): 179–187. doi:10.1093/hwj/5.1.179. JSTOR4288169.
van den Heuvel 2019, pp. 29. Pannekoek first published his suspicions on the variability of Polaris as a footnote in 1906 (Pannekoek 1906, p. 148). His observations were published in 1913 (Pannekoek 1913) van den Heuvel, Edward (2019). "Anton Pannekoek's Astronomy in Relation to his Political Activities, and the Founding of the Astronomical Institute of the University of Amsterdam". In Tai, Chaokang; van der Streen, Bart; van Dongen, Jeroen (eds.). Anton Pannekoek: Ways of Viewing Science and Society. Amsterdam: Amsterdam University Press. pp. 9–23. doi:10.2307/j.ctvp7d57c.4. ISBN9789462984349. Pannekoek, Anton (1906). "The luminosity of stars of different types of spectrum". Proceedings of the Section of Science, Koninklijke Akademie van Wetenschappen. 9 (2): 1192–1199. Bibcode:1906KNAB....9..134P – via KNAW Digital Library. Pannekoek, Anton (1913). "The variability of the Pole-star". Proceedings of the Section of Science, Koninklijke Akademie van Wetenschappen. 15 (1): 134–148 – via KNAW Digital Library.