@article{article, title  = {{Temporal and Periodic Analysis of Penumbra–Umbra Ratio for the Last Four Solar Cycles}},

 publisher = {{Springer Science and Business Media LLC}},

 url = {{http://dx.doi.org/10.1007/s11207-024-02263-5 }},

 year = {{2024}},

 month = {{2}},

 author = {{Chowdhury P and Kilcik A and Saha A and Rozelot J-P and Obridko V and Erdélyi R}},

 doi = {{10.1007/s11207-024-02263-5}},

 volume = {{299}},

 journal = {{Solar Physics}},

 issue = {{2}},

 pages = {{19}},

 note = {{Accessed on 2024/12/22}}}