Please understand my low command of English. I'm now reading the thesis about DSMC, its author is Usami, Japanese and professor. I'm wondering that, he develop the very powerful method to use the DSMC at continuum region. DSMC has problem of high computational expense. But Usami develop the new collision model and its result was excelent. Result shows that cell size can be lengthend to 15 times of mean free path. But despite his achivement, I can't find its review or application thesis to validate the model which was written by other author,not Usami. So, does it have some kind of problem? If it have, what kind of problem? I want to know, can I refer his thesis to my thesis? please help. His thesis was announced at Rarefied Gas Dynamics Symposium.