Complex sentence: His first wife was Victoria Isaevna Libina, to the memory of which the famous book is dedicated: she died by peritonitis in 1961 during a boat trip on the Volga, where apparently there was no doctor on board.
Split into simpler sentences: His first wife was Victoria Isaevna Libina: the famous book is dedicated to her memory. She died of peritonitis in 1961 during a boat trip on Volga: apparently, there was no doctor on board.