共 50 条
- [23] Polyethylene and polypropylene in the 21st century. ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, 2000, 219 : U548 - U548
- [26] Social security in the 21st Century. AMERICAN REVIEW OF PUBLIC ADMINISTRATION, 1998, 28 (04): : 412 - 416
- [30] Applied Demography in the 21st Century. POPULATION STUDIES-A JOURNAL OF DEMOGRAPHY, 2009, 63 (02): : 200 - 201