Periodical changes in the activity of the Encke comet Zdeněk Sekanina (1961) Acta Universitatis Carolinae. Mathematica Similarity:
Atmospheric precipitation and directly measured cometary characteristic Zdeněk Sekanina (1964) Acta Universitatis Carolinae. Mathematica et Physica Similarity:
Absolut brightness of comet Ikya-Seki 1965 f and of other comets of Kreutz's group Jiří Bouška (1966) Acta Universitatis Carolinae. Mathematica et Physica Similarity: