* His role in the struggle for Zimbabwean independence: He founded the Zimbabwe African People's Union (ZAPU) in 1961 and led the armed struggle against Rhodesian rule.
* His political leadership: He served as a Minister in the first Zimbabwean government after independence in 1980.
* His contribution to the peace process: He played a key role in the Unity Accord of 1987, which brought together ZAPU and ZANU, the two main liberation movements, under the leadership of Robert Mugabe.
Although Nkomo didn't write any books, there are likely biographies and studies written about him and his life.
If you are interested in learning more about Joshua Nkomo, I recommend searching for books and articles about him, or looking at his biography on websites like Wikipedia.