From September 20 to October 22, Professor Zhangsheng, doctoral supervisor of History Department of Nanjing University and vice-superintendent of Nanjing Massacre Graduate School and Professor Yang Xiaming of Jiangsu Administration College went to U.S. National Archives and Records Administration to collect valuable materials of Nanjing Massacre. At present, a batch of scholars went to Japan, Germany, Britain and Taiwan to seek for irrefutable evidences of Nanjing Massacre. They hope to find the detailed historical materials to prove Nanjing Massacre.

Zhangsheng told the reporter that in 1937, America had cracked the code of diplomatic information of Japan. In U.S. National Archives and Records Administration, there are over 10 thousand pages of decoded Japanese diplomatic files. Experts found a valuable top-secret file. It is a cipher telegram that Japanese prime minister sent to Japan Embassy in America on January 17, 1938.

"When I came to Shanghai several days ago, I investigated reports of atrocities by Japanese invaders in Nanjing and other areas. According to eyewitnesses and some letters, not less than 300 thousand Chinese people were killed. Robbery, rape, including raping children, the killing stooped before several weeks. " Zhangsheng said that it was the irrefutable evidence referring to 300 thousand Nanjing residents killed by Japanese invaders earliest.

Professor Zhangsheng also found many diaries of Japanese soldiers. Zhangsheng and other scholars think these diaries are proofs of "heroism" of Japanese soldiers. But Zhangsheng said that these diaries and letters became irrefutable evidences of Japanese invaders.

In addition, Zhangsheng thinks that there should be the Memorial Halls of the Victims in Nanjing Massacre by Japanese Invaders in other cities besides in Nanjing. In America and Europe, memorials of "slaughter by Nazi" are set up in many cities.