By Vaudine England
BBC News, Hong Kong
Bao Pu also published deposed communist Zhao Zhiyang's memoirs
A book about Chinese history banned in China has gone on sale in Hong Kong.
A Hong Kong-based publisher, Bao Pu, was able to release the book because of Hong Kong's guaranteed rights of freedom of the press and expression.
The mainland academic who wrote the book, Xiao Jiansheng, spent 20 years researching and writing the critical look at China's past.
Now he is being watched ahead of Beijing's celebrations of 60 years of communist party rule this week.
History and civilisation
Mr Xiao's book - called Chinese Civilisation Revisited - does not sound like a blockbuster.
But by daring to question the official version of China's 5,000 years of history and culture, the weighty academic work achieved notoriety even before it hit the shops in Hong Kong.
At first, publication was approved in China. But after officials read it, the book's re-writing of history - without touching directly on the past 60 years of communist rule - provoked the ban.
Then Bao Pu stepped in. His father, Bao Tong, was the most senior Chinese official jailed after the 1989 Tiananmen democracy protests.
Bao Pu lives in Hong Kong - so he can publish and sell the book freely.
But his complex background has put the author, Mr Xiao, under more pressure.
He has had to quit his newspaper job in Hunan province, China. Every time a reporter calls him, he has to report who called and what they asked.
In an exclusive extract from the book, published in Hong Kong's South China Morning Post newspaper, Mr Xiao explains that he was motivated to write his book by the death of his grandfather.
Angered by the forced communalisation of his farm and village in 1958, Mr Xiao's grandfather went on hunger strike and died, he recalled.
Mr Xiao went on to work in the communist party's propaganda department but, appalled at unnecessary poverty and disruption in rural areas, he wrote an article in 1974 which got him into trouble.
He has no regrets, he said.
"I believe that Chinese society and civilisation are progressing after all," he said.
"No-one can stop the footsteps of history from moving forward," said Mr Xiao.