Karst evolution, sinkholes, caves, springs, lakelets: Pasvalys town and peculiarities of Biržai Regional Park / Compiled by Mikulėnas V., Satkūnienė I., Gedminienė L., Uogintas D. Field trip guide. 3rd Crossing the Palaeoentological-ecological gap – CPEG. Conference. 31st August 2023. Nature Research Centre, Geological Society of Lithuania, Lithuanian Geological Survey. Vilnius, 2023 – 22 p.