@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 2025/06/28}}}