BAIMOLDA DOSSAN; CECHAK TOMAS; SHYNGYSOVA SH. X-RAY FLUORESCENCE RESEARCH OF SULPHUR AND ASH CONTENTS IN THE COALS OF KAZAKHSTAN. European Research Materials, [S. l.], n. 1, 2022. Disponível em: https://ojs.scipub.de/index.php/ERM/article/view/490. Acesso em: 16 apr. 2026.