PETRELIUS, A. Uppsökandet af den Rysk-Skandinaviska gradmätningens inom Finland belägna triangelpunkter. Fennia - International Journal of Geography, [S. l.], v. 3, n. 1, p. 1–14, 1890. Disponível em: https://fennia.journal.fi/article/view/155720. Acesso em: 10 jan. 2025.