Järvinen, O., R. A. Väisänen, and Y. Haila. “Estimating Relative Densities of Breeding Birds by the Line Transect Method. III. Temporal Constancy of the Proportion of Main Belt Observations”. Ornis Fennica 53, no. 2 (July 1, 1976): 40–45. Accessed May 9, 2024. https://ornisfennica.journal.fi/article/view/132896.