Underground "illegal" Jewish Calendars from the Soviet Union

A large collection of rare books I recently acquired contained a collection of Jewish Calendars from the Soviet Union. Due to fear of government reprisals, these calendars were handwritten and copied in secret. A few of the calendars, which span several decades, are photocopies of handwritten calendars.
A vivid reminder, of the determination and efforts of some of Soviet Jewry to preserve their faith, despite the constant fear of repercussions.