Pavlichenko_Fan_Club [comrade/them]

A few old Bolsheviks wrote biographies that will give you clear, concrete details of underground activity. See “Twenty Years in Underground Russia: Memoirs of a Rank-and-File Bolshevik” by Cecilia Bobrovskaya

https://www.marxists.org/archive/bobrovskaya/twenty-years/index.htm

https://www.marxists.org/archive/lenin/works/1902/sep/00.htm “A Letter to a Comrade on Our Organisational Tasks”