The Zhaohao Wu letters mainly consist of twenty-eight handwritten letters from Zhaohao Wu and others in Germany and in Moscow to his younger brother Zhaofa Wu in the U.S. between 1923 and 1929. Zhaohao Wu wrote extensively to his brother about his understanding and enthusiasm in the socialist movement, his opinions on Chinese politics, and his life abroad as an international student. One additional letter from Liang Qichao to his son-in-law, Chou Kuo Hsien about the establishment of the Songpo Library in 1918 was later added to the collection.