Amber Gemstones Sorting By Colour. Elektronika ir Elektrotechnika, [S. l.], v. 23, n. 2, p. 10–14, 2017. DOI: 10.5755/j01.eie.23.2.17993. Disponível em: https://eejournal.ktu.lt/index.php/elt/article/view/17993.. Acesso em: 6 dec. 2025.