Laurila 1960, p. 194. Laurila, Simo (1960), "Geodimeter", Electronic Surveying and Mapping: Part 1, Fundamentals of Electronic Surveying, Institute of Geodesy, Photogrammetry and Cartography, The Ohio State University, pp. 194–203, hdl:2027/uiug.30112007333120, OCLC58011617, retrieved May 6, 2021 – via HathiTrust
Laurila 1960, p. 194. Laurila, Simo (1960), "Geodimeter", Electronic Surveying and Mapping: Part 1, Fundamentals of Electronic Surveying, Institute of Geodesy, Photogrammetry and Cartography, The Ohio State University, pp. 194–203, hdl:2027/uiug.30112007333120, OCLC58011617, retrieved May 6, 2021 – via HathiTrust