History of Sunspot Research and Forecast of the Maximum of Solar Cycle 25

[1] Abrahams P.(2009)The meaning of the 'anniversary of the telescope' J. Antique Telesc. Soc. 30 3-4

[2] Arlt R.(2011)The sunspot observations by Samuel Heinrich Schwabe Astron. Nachr. 332 805-814

[3] Arlt R.(2013)Sunspot positions and sizes for 1825– 1867 from the observations by Samuel Heinrich Schwabe Mon. Not. R. Astron. Soc. 433 3165-3172

[4] Leussu R.(2016)Sunspot positions, areas, and group tilt angles for 1611–1631 from observations by Christoph Scheiner Astron. Astrophys. 595 A104-533

[5] Giese N.(2020)Historical sunspot records Living Rev. Sol. Phys. 17 60-2492

[6] Mursula K.(1975)Heinrich Samuel Schwabe, 1789–1875 J. Brit. Astron. Assoc. 85 532-325

[7] Usoskin I. G.(2020)Number of sunspot groups from the Galileo–Scheiner controversy revisited Mon. Not. R. Astron. Soc. 496 2482-103

[8] Arlt R.(2008)Thomas Harriot: The first telescopic astronomer J. Br. Astron. Assoc. 118 315-418

[9] Senthamizh Pavai V.(2017)New reconstruction of the sunspot group numbers since 1739 using direct calibration and "backbone” methods Astron. Astrophys. 602 A69-370

[10] Schmiel C.(2014)Revisiting the sunspot number. A 400-year perspective on the solar cycle Space Sci. Rev. 186 35-462

[1] Abrahams P.(2009)The meaning of the 'anniversary of the telescope' J. Antique Telesc. Soc. 30 3-4

[2] Arlt R.(2011)The sunspot observations by Samuel Heinrich Schwabe Astron. Nachr. 332 805-814

[3] Arlt R.(2013)Sunspot positions and sizes for 1825– 1867 from the observations by Samuel Heinrich Schwabe Mon. Not. R. Astron. Soc. 433 3165-3172

[4] Leussu R.(2016)Sunspot positions, areas, and group tilt angles for 1611–1631 from observations by Christoph Scheiner Astron. Astrophys. 595 A104-533

[5] Giese N.(2020)Historical sunspot records Living Rev. Sol. Phys. 17 60-2492

[6] Mursula K.(1975)Heinrich Samuel Schwabe, 1789–1875 J. Brit. Astron. Assoc. 85 532-325

[7] Usoskin I. G.(2020)Number of sunspot groups from the Galileo–Scheiner controversy revisited Mon. Not. R. Astron. Soc. 496 2482-103

[8] Arlt R.(2008)Thomas Harriot: The first telescopic astronomer J. Br. Astron. Assoc. 118 315-418

[9] Senthamizh Pavai V.(2017)New reconstruction of the sunspot group numbers since 1739 using direct calibration and "backbone” methods Astron. Astrophys. 602 A69-370

[10] Schmiel C.(2014)Revisiting the sunspot number. A 400-year perspective on the solar cycle Space Sci. Rev. 186 35-462