R. Schlichenmaier
Jurčák Jan
,
Rezaei R.
,
Bello González N.
,
Schlichenmaier R.
,
Vomlel Jiří
:
The magnetic nature of umbra-penumbra boundary in sunspots
,
Astronomy & Astrophysics vol.611, L4
[2018]
DOI:
10.1051/0004-6361/201732528