Thomas J. Bogdan-NCAR/UCAR
Peter A. Gilman-NCAR/UCAR
I. Lerche
R. Howard
Distribution of sunspot umbral areas: 1917-1982
The Astrophysical Journal
1988-04-01
327
1
451-456
article
Refereed
Copyright 1988 the American Astronomical Society.
http://dx.doi.org/10.1086/166206
http://n2t.net/ark:/85065/d70g3js1