Perhaps you should try some spelling variations:
thieu tach » thien hach, chiet tach, chieu sach
thanh tung » thanh cong
phan chung » phan cung, phan hung, phan thuong
hoc thieu » toc thieu, hoc hien
ha nhung » hoa nhung, hay nhung, pha nhung
tan toan » tan tran, van toan, dan toan
tap toan » tap doan, tap quan, bai toan

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc thieu tach - thanh tung ((ha nhung) or (phan chung)) cong ((tan toan) OR (tap toan)) tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc thieu tach - thanh tung ((ha nhung) OR (phan chung)) cong ((tan toan) OR (tap toan)) tap.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc thieu tach - thanh tung ((ha nhung) or (phan chung)) cong ((tan toan) OR (tap toan)) tap".
• Adding a wildcard symbol may retrieve word variants: hoc thieu tach - thanh tung ((ha nhung) or (phan chung)) cong ((tan toan) OR (tap toan)) tap*.