PATRIARCH Deng Xiaoping is said to be waging one of his last, and most important, battles - the preservation of his legacy. Chinese sources said yesterday Mr Deng, who turns 89 in August, had recently given personal instructions for the final editing of The Selected Works of Deng Xiaoping, 1983-1992 . A collection of his major speeches and internal writings in the most crucial period of reform, Selected Works is expected to be released next month. That Mr Deng has been able to give instructions for the final phase of the preparation of the tome is evidence that, despite his steadily declining health, the senior leader still has command of his mental faculties. The thick volume covers directives and speeches Mr Deng gave for the transition of the command economy to a ''socialist market economy''. Most significantly, the book contains internal orders that the patriarch issued for the handling of the two most potent challenges to the Chinese Communist Party: the student movements of late 1986 and early 1989. ''I am satisfied with the first half of the book, but not so happy with the latter half,'' Mr Deng reportedly told the team of editors of Selected Works . ''We have to do more work with the later speeches.'' It is believed that the second half of the book, which covers circumstances leading to, as well as the quelling of, the June 4, 1989, Tiananmen Square protests, is more problematic because Mr Deng does not want to be implicated in the decision to open fire on the demonstrators. Chinese sources said Mr Deng had excised material that pointed to his personal role in the deployment of troops against the students and other dissidents in early June 1989. The patriarch also played down his involvement in the decision, in early 1988, to speed up economic development and price reforms, which led to hyperinflation and other disruptions later that year. The sources added that, by establishing the ''perpetual correctness'' of his 14-year reform gambit, Mr Deng wanted to ensure that his market reforms would not be slowed down after his death. The team of editors is led by the vice-head of the party's propaganda department, Zheng Bijian, the former vice-head of propaganda, Gong Yuzhi, and the director of the Central Party Literature Research Centre, Pang Xianzhi. Because of last-minute instructions from Mr Deng, the volume's publication, originally scheduled for July 1 - the ''birthday'' of the party - had been postponed to late next month or August. The sources said the Chinese propaganda machinery would launch a nationwide campaign to ''learn from Deng Xiaoping thought'', upon the release of the volume. ''Deng thought is seen as the most powerful weapon that can bind the nation together at a time when the country is on the verge of being pulled apart by economic difficulties,'' a Chinese source said. ''For example, senior cadres would invoke Deng thought to urge regional officials and entrepreneurs to do their part in controlling hyper-inflation and the runaway money supply.'' The campaign to learn from Deng thought will be led by President Jiang Zemin, who is eager to use his status as the patriarch's designated heir to consolidate his position. In the past two months, Mr Jiang has masterminded high-level seminars on Deng thought held in Shanghai, his power base. Chinese sources said that while Mr Deng's mind remained lucid, his physical health continued to be unsatisfactory. ''Deng is suffering from senile conditions, comparable to those affecting Mao [Zedong] in the last months of his life,'' a political source said. ''He had a bad fall, which might have been triggered by a minor stroke, in the spring. While he has recovered from that fall, his conditions will not allow him to travel out of Beijing any time soon.'' The source said Mr Deng had become more and more dependent on his children and on members of his office for information, and for the drafting of instructions that were later issued in his name. In 1983, Mr Deng published Selected Works of Deng Xiaoping 1975-1982 , which was launched as a ''guiding light'' for the nation's bid to achieve modernisation. He has repeatedly given instructions that the official verdict on the June 4 incident not be overturned.