You mean sources of Mao’s support for Taiwan independence?
1928, members of Taiwan Communist Parties who escaped Japanese persecution announced the formation of their party with the support of the CCP in Shanghai Their party mission statement:
2．台湾人民独立万岁 (Viva Taiwanese Independence)
3．建立台湾共和国 (Formation of the Taiwan Republic)
In 1936, Edgar Snow interviewed Mao, and published in "Red Star over China"
Mao responded unequivocally:
It is the immediate task of China to regain all our lost territories, not merely to defend our sovereignty south of the Great Wall. This means that Manchuria must be regained. We do not, however, include Korea, formerly a Chinese colony, but when we have re-established the independence of the lost territories of China, and if the Koreans wish to break away from the chains of Japanese imperialism, we will extend them our enthusiastic help in their struggle for independence. The same thing applies for Taiwan.
In 1947, Mao made a statement on the radio in response to the KMT’s 228 massacre of Taiwanese elites.
Our armed forces led by the Chinese Communist Part completely supports the struggle of the people of Taiwan against Chiang Kai-shek and the KMT. We support Taiwan independence. We support Taiwan form a nation with self-determination.
There are also such statements from Zhou En-lai. They didn’t claim Taiwan as part of its territory until Chiang boldie got here.