Akhtemov, Z., Y. Tsap, and V. Malaschuk. “Sunspot Magnetic Fields in Solar Cycle 24 on Measurements at Crimea and Mount Wilson”. Acta Astrophysica Taurica, vol. 6, no. 1, Mar. 2025, pp. 19-23, https://astrophysicatauricum.org/index.php/aat/article/view/105.