Balaišis, P., D. Eidukas, and L. Gočelkienė. “Electronic Payment Systems for Communications Services”. Elektronika ir Elektrotechnika 91, no. 3 (March 19, 2009): 3-8. Accessed December 22, 2024. https://eejournal.ktu.lt/index.php/elt/article/view/10269.