Ferry, Björn, Johan Ekenstedt, and Martin Green. 2021. “Densities of the Eurasian Threetoed Woodpecker Picoides Tridactylus Calculated from Sap Row Surveys Are on Par With Estimates from Fixed Route Bird Censusing”. Ornis Svecica 31 (September). Lund, Sweden:94–106. https://doi.org/10.34080/os.v31.22416.