L. Toivari and O. Lindqvist, “The Marsh Warbler (Acrocephalus palustris) and Blyth´s Reed Warbler (Acrocephalus dumetorum) in the district of Lappeenranta, Summer 1960”, Ornis Fenn, vol. 38, no. 3–4, pp. 93–95, Dec. 1961.