I am not sure this source is translated into English, but it is especially interesting because it is, so to say, "iz pervykh ruk": Nikolai Morozov. Povesti moei zhizni. 2 vols. Moskva: Izd-vo Akademii nauk SSSR, 1961. Epecially see vol. 2 on their years in Shlisselburg fortress. Julia Trubikhina New York University