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

 url = {{http://dx.doi.org/10.21203/rs.3.rs-3177659/v1 }},

 year = {{2023}},

 month = {{7}},

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

 doi = {{10.21203/rs.3.rs-3177659/v1}},

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