Husak, Mirko, Roman Brajša, and Dragan Špoljarić. 2021. “On the Determination of the Solar Rotation Elements I, Ω and Period Using Sunspot Observations by Ruđer Bošković in 1777”. Rudarsko-geološko-Naftni Zbornik (The Mining-Geological-Petroleum Engineering Bulletin) 36 (3). https://doi.org/10.17794/rgn.2021.3.6.