Search results
- Daily relative sunspot numbers 1818-1848: Reconstruction of missing observations / V. Letfus . [Prague] : Astronomical Institute of the Academy of Sciences of the Czech Republic, 1996 . 5, [50] s. [1, currently available 1]
- Co víme o vesmíru / Miloslav Kopecký, Boris Valníček, Vojtěch Letfus . Praha : Lidová demokracie, 1960 . 137 s., [24] s. příl. [1, currently available 1]