Ivkov, Vesna. “Tracing the Oldest Audio Recordings of Vocal Musical Tradition of Germans in Bačka: The Field Research of Gustav Kipers-Sonenberg in Bačka”. Etnoantropološki Problemi Issues in Ethnology and Anthropology , vol. 8, no. 2, Aug. 2013, pp. 585-96, doi:10.21301/EAP.v8i2.12.