Looking for Primary Source Material for Political Violence in late imperial russia (pre-nicholas II)

Sergei Stepniak's Underground Russia is good, but unfortunately out of print for the last century or so. You can read parts of it here and here.

Here is the recommended reading list from the book Five Sisters: Women Against the Tsar, ed. by Barbara Engel and Clifford Rosenthal:

Vera Zasulich by Jay Bergman, Stanford Uni. Press
Hidden Springs of the Russian Revolution by Catherine Breshovsky. Stanford
Training the Nihilists: Education and Radicalism in Tsarist Russia by Daniel Brower, Cornell Uni. Press
What Is to Be Done? by Chernyshevsky
The Feminist Movement in Russia, 1900-1917 by Linda Edmondson, Standford Uni. Press
Mothers and Daughters: Women of the Intelligentsia in 19th Century Russia by Barbara Engels
Memoirs of a Revolutionist by Vera Figner
Red Prelude: The Life of Russian Terrorist Zheliabov by David Footman, Cresset Press
Young Russia: the Genesis of Russian Radicalism in the 1860's by Abbott Gleason
Siberia and the Exile System by George Kerman
A Convergence of Lives: Sofia Kovalevskaia: Writer, Scientist, Revolutionary by Ann Koblitz
A Russian Childhood by Sofia Kovalevskaia
Underground Russia and A Female Nihilist by Stepniak
Memoirs of a Revolutionist by Peter Kropotkin
Historical Letters by Peter Lavrov, Univ. of California Press
Sonya Kovalevsky: Her Recollections of Childhood by Anna Leffler
Knowledge and Revolution: The Russian Colony in Zurich 1870-1873 by JM Meijer
Sergei Nechaev by Philip Pomper, Rutgers Univ. Press
Fathers and Daughters by Cathy Porter, Vitago Press
The Family of Imperial Russia ed. by David Rnsel, Univ. of Illnois Press
The Women's Liberation Movement in Russia: Feminism, Nihilism, and Bolshevism by Richard Stites, Princeton Univ. Press
The First Women Russian Physicians by Jeannette Tuve
Roots of Revolution by Franco Venturi
Road to Revolution: A Century of Russian Radicalism by Avtalum Yarmolinsky