Which three do Zuo Si's three capitals refer to?

They are Wudu Fu, Dewey Fu and Shudu Fu.

1 and Sandu Fu are the works of Zuo Si in Jin Dynasty. They are Wudu Fu, Dewey Fu and Shudu Fu. It took ten years to make, and it was passed down as a classic for a while. Luoyang paper is expensive. After reading Sandu Fu, Huangfu Mi spoke highly of it and made a preface to this article.

2. It does not refer to Sandu, but to Wudu Fu, Du Wei Fu and Shu Du Fu, which describes the general situation of Wei, Shu and Wu. Sandu Fu was written by Zuo Si. Zuo Si was born in Linzi, Qi (now Zibo, Shandong). Famous writers in the Western Jin Dynasty. Zuo Si grew up ugly but talented.

During the Eastern Han Dynasty, Ban Gu's "Fu of Twin Cities" and Zhang Heng's "Fu of Twin Cities" became masterpieces handed down from generation to generation. After Zuo Si came to Luoyang, he planned to imitate these two poems, Sandu Fu. In order to write Sandu Fu, Zuo Si conceived and created it behind closed doors for ten years, thinking that he was not knowledgeable, and asked the court to be the secretary of Lang and read the Imperial Library, which enriched the connotation of the article.

Introduction to Zuo Si:

Zuo Si (250? ~305? ), the word Taichong, was born in Linzi, Qi (now Zibo, Shandong). Famous writers in the Western Jin Dynasty. Zuo Si grew up ugly but talented. During the reign of Emperor Wu of Jin Dynasty, my sister Juicy Zuo was elected to the palace, and her family moved to Luoyang as a doctor. After Hui Jin proclaimed himself emperor, he attached himself to the powerful Krabi and became an important member of the "Twenty-four Friends" literati group.

Zuo Si's family background is Confucianism. His father, whose real name is Zuo, started as a small official and once worked as an assistant to the emperor, Taiyuan Xiang and Yiyang Taishou. I studied calligraphy and drum set when I was young, but I failed. Later, with my father's encouragement, I became angry and diligent.

Zuo Si is ugly, clumsy and difficult to make friends, but his words are magnificent. He once wrote Qi Du Fu in one year. In the eighth year of Taishi (272), his sister Juicy Zuo was elected to the palace, and his family moved to Luoyang as a doctor. During Yuan Kang's reign, Zuo Si took part in a tour of twenty-four friends of the literati group at that time and gave a lecture on Hanshu to Krabi.