This book focuses on the sound recordings of ethnic Estonian informants, prepared between 1916 and 1918 in five German prisoner-of-war camps. Before 1918, Estonia was part of the Russian empire, and during World War I ethnic Estonian conscripts fought in the Russian army. The duration of available audio material is about one hour and it is presented on the CD accompanying the book. The original audio material is preserved in two archives: wax rolls at the Ethnologisches Museum in Berlin-Dahlem (Phonogramm-Archiv) and shellac discs at the Humboldt-Universität zu Berlin (Lautarchiv). This volume consists of nine chapters written by authors working in diverse fields such as archival or folklore studies, history, linguistics, and musicology.