USE OF ISOTOPE DILUTION METHOD FOR DETERMINATION OF Ce, Sm, AND Yb ABUNDANCES IN GEOLOGICAL SAMPLES BY ICP-MS oleh Cao Đông Vũ, Trương Đức Toàn, Nguyễn Đăng Khánh, Đỗ Tâm Nhân, Võ Trần Quang Thái, Nguyễn Lê Anh, Nguyễn Việt Đức, Nguyễn Giằng, Nguyễn Trọng Ngọ