What are the masterpieces?

Degree:1+1=1; Du Jia Du Yu; Du Xue; Du Jing; Laozi and DuDu: Analysis of Du Xue: Calligraphy monographs: Du Feng Zhu Yun: Du Zhi's Unique Calligraphy Font, Unique Calligraphy Course, Du Xue's Dictionary, Du Zhi Ink, etc. His masterpiece "Degree" is the first philosophical monograph on degree in the history of Chinese and foreign thoughts. This book is a combination of China, Britain, France, Japan and Korea and has spread to many countries.