Chernoyarov, O. V., Y. A. Kutoyants, and M. Marcokova. “On Frequency Estimation for Partially Observed System With Small Noises in State and Observation Equations ”. Communications - Scientific Letters of the University of Zilina, Vol. 20, no. 1, Mar. 2018, pp. 67-72, http://journals.uniza.sk/index.php/communications/article/view/48.