Complex sentence: It was then that the 19-year-old Bukovsky wrote his critical notes on the Komsomol, later termed "Theses on the Collapse of the Komsomol" by the KGB.
Split into simpler sentences: It was then that the 19-year-old Bukovsky wrote his critical notes on the Komsomol. Later they were given the title "Theses on the Collapse of the Komsomol" by the KGB.