• The earliest Ordovician trace fossils Cruziana and Rusophycus from BalticaPärnaste, Helje; Toom, Ursula; Popov, Leonid E.Estonian journal of earth sciences2023 / p. 154 https://doi.org/10.3176/earth.2023.63
  • The lower cambrian trilobite zonation of EstoniaPärnaste, HeljeXI Baltic Stratigraphical Conference : abstracts and field guide2024 / p. 31 https://www.ester.ee/record=b5696260*est https://files.geocollections.info/17aa8067-966a-428d-8bd4-cc22e36cce73.pdf