Perhaps you should try some spelling variations:
trinh thiet » trinh viet, trinh thi
trinh thuat » trinh luat, trinh thuc, trinh chat
dung thuong » dung trong, hang thuong, cong thuong
chieu sang » chieu xanh, hieu lang, nhieu tang
chieu sach » chinh sach, chiet tach, chieu xanh
thuong van » thong van, truong van, thuong va
van chat » cao chat
van van » van ban, tan van, san van

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ho ((chieu sang) or (chieu sach)) - hanh ((trinh thuat) OR (trinh thiet)) dung thuong van van chat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ho ((chieu sang) OR (chieu sach)) - hanh ((trinh thuat) OR (trinh thiet)) dung thuong van van chat*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho ((chieu sang) or (chieu sach)) - hanh ((trinh thuat) OR (trinh thiet)) dung thuong van van chat*".