Pre-concentration procedure of sea-water samples at the field for the simultaneous determination of radionuclides activity (90Sr, 137Ra, 239,240Pu, U and Th) - Nguyễn Trọng Ngọ.; Lê Như Siêu.; Mai Thị Hương.; Nguyễn Mong Sinh.; Nguyễn Thanh Bình.; Nguyễn Văn Phúc.; Trương Ý.