East China\'s Jiangsu Province has released a collection of historical documents recording the notorious Nanjing Massacre in which more than 300,000 Chinese people were killed by Japanese aggressor troops in 1937. More than 100 experts and scholars spent 10 years to compile the works, two thirds of which had hardly been seen before, said Zhang Xianwei, chief editor of the collection. The collection, jointly released by Jiangsu People\'s Publishing Limited and Phoenix Publishing and Media Group on Wednesday, was the most elaborate and systematic historical works on the incident, said Zhang. According to Zhang, earlier documents about the Nanjing Massacre had no more than 2 million Chinese characters, while there were 40 million characters in this collection, containing first-hand information translated from English, Japanese, German, Italian and Russian. \"Some Japanese did not admit the crimes they did, pushing us to carry out a thorough study,\" said Zhang, adding the collection will help both Chinese and Japanese people, especially the youth to have a correct understanding of the incident. Japanese aggressor troops occupied Nanjing in eastern China on Dec. 13, 1937, and began a six-week massacre. Chinese records show more than 300,000 people not only disarmed soldiers, but also civilians were brutally murdered and thousands of women raped.