Perhaps you should try some spelling variations:
trung duong » trung uong, trung dung, trung dong
trung xuong » trung uong, truong huong, truong vuong
theo chieu » theo tieu, ho chieu, theo chu
chieu sach » chinh sach, chiet tach, chieu sang
nhanh lang » nhanh quang, nhanh thang, nhanh dong
nhan dang » nhan dan, phan dang, tran dang
dan toan » van toan, dan than, manh toan
toan cao » toan ban, toan tap

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

• Performing a fuzzy search may retrieve terms with similar spellings: theo chieu sach - ((nhanh lang) or (nhan dang)) cua ((trung xuong) OR (trung duong)) dan toan cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: theo chieu sach - ((nhanh lang) OR (nhan dang)) cua ((trung xuong) OR (trung duong)) dan toan cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "theo chieu sach - ((nhanh lang) or (nhan dang)) cua ((trung xuong) OR (trung duong)) dan toan cao".
• Adding a wildcard symbol may retrieve word variants: theo chieu sach - ((nhanh lang) or (nhan dang)) cua ((trung xuong) OR (trung duong)) dan toan cao*.