China has launched the second major revision of Chinese history books, mainly to correct errors made in the first revision during the Cultural Revolution (1966-76), the chief editor of the revision project said.

"Due to restrictions in terms of politics and academics, the first amendment has some shortages and defects, which are inconvenient to readers," said Xu Jun, who leads the revision project on Twenty-Four Histories and the Draft History of Qing, which is expected to be finished in 2015.

The primary draft is expected to be finished in 2012 and by the end of 2015, the Beijing News reported.

The Twenty-Four Histories is a collection of Chinese historical books covering a period of proto-history and history from 3,000 BC to the Ming Dynasty in the 17th century. The entire set contains about 40 million words. The Draft History of Qing covers the Qing Dynasty from 1616 to 1911.

"The books are an authoritative source of information on Chinese civilization and are a unique treasure for China," Zhou Huaiyu, a professor from the department of Ancient Chinese History at Anhui University, told the Global Times Monday.

Xu said the first historical revision took 20 years, ending in 1958, but was interrupted and distorted by the Cultural Revolution (1966-76), which brought great calamity to the country and people, causing the most serious setbacks and most damaging losses.

When revising the books, even punctuation was altered to satisfy the politics of the time, according to Xu.

"All sentences used to praise feudal kings, generals and ministers should not end with exclamation marks," Xu said. "While the texts describing peasant uprisings should be reduced to a single paragraph."

In 2005, Zhonghua Book Company, one of oldest publishers in China, wrote a proposal to correct the defects. Premier Wen Jiabao approved the proposal and the project has been granted special funds.

Compiling and revising historical books and records in a peaceful and prosperous era is a fine Chinese tradition, Liu Binjie, director general of the General Administration of Press and Publication, said in January at a seminar celebrating the publication of Chinese Canonical Literature, which took 20 years to compile.

"Every person should try to get a true history from historical books. Only by respecting history and learning from experience and mistakes we made in the past can we improve," Chen E'fa, a master's degree candidate in history at South China Normal University, told the Global Times.

Professor Zhou said history books can hardly be 100 percent accurate. Compliers have different interpretations on issues depending on different eras and countries, he added.