R. Leussu

Properties of sunspot cycles and hemispheric wings since the 19th century

R. Arlt, I. Usoskin, K. Mursula, 2016 .

Inconsistency of the Wolf sunspot number series around 1848

R. Arlt, I. Usoskin, K. Mursula, 2013, 1310.8443.

Sunspot positions and sizes for 1825–1867 from the observations by Samuel Heinrich Schwabe

R. Arlt, I. Usoskin, N. Giese, 2013, 1305.7400.

Wings of the butterfly : sunspot groups for 1826–2015

C. Denker, R. Arlt, I. Usoskin, 2017 .