This hardcover book, written by Danan Gu, is a valuable resource for those interested in the topic of aging. The book is part of the Encyclopedia of Gerontology and Population Aging series, and covers a range of topics related to aging. The book is written in English and is a great addition to any library. The book is ideal for those interested in the biological, social, and economic aspects of aging. It provides a comprehensive overview of the field of gerontology and population aging, and is an essential resource for anyone looking to gain a deeper understanding of these topics. Whether you are a researcher, a policymaker, or simply curious about the subject, this book is sure to provide you with valuable insights.