莫言研究三十年 = Mo Yan study : from 1980s to 2010s / 主编杨守森, 贺立华 ; 执行主编丛新强, 孙书文. (OCLC #844719198)

When there are only three volumes in a Chinese or Japanese set, it may be enumerated using these characters instead of numbers:

• 上 – (first)
• 中 – (middle, shown above)
• 下 – (last)

In my library, we label these on the spine with v.1, v.2, v.3 respectively.

If a set only has two volumes, it may only use 上 and 下.