Pavlāns, Vitālijs, Eduards Purviņš, and Sandra Ežmale. “ELECTRONIC INVOICING”. HUMAN. ENVIRONMENT. TECHNOLOGIES. Proceedings of the Students International Scientific and Practical Conference, no. 20 (April 20, 2016): 162–167. Accessed May 7, 2024. https://journals.ru.lv/index.php/HET/article/view/3534.