Keio Correspondence Course: Yasuo Yokoyama, Introduction to Sociology This is a foundational academic book on sociology published in 1981. Although it's from that time, it contains the basics of sociology and is a valuable document for deepening understanding when tracing the historical background, ideas, and transitions of the time. The case shows signs of aging, but it's clean except for some writing in a part of the table of contents. There's a library stamp on the last page. Please check the photos and purchase with your understanding.