Gavrijaseva, Alina, Olev Martens, and Raul Land. “Acoustic Spectrum Analysis of Genuine and Counterfeit Euro Coins”. Elektronika ir Elektrotechnika 21, no. 3 (June 5, 2015): 59-57. Accessed October 4, 2022. https://eejournal.ktu.lt/index.php/elt/article/view/10384.