Perhaps you should try some spelling variations:
thieu sach » chieu sach, hieu cach, theo sach
thien hach » thien thanh, hien hanh
nhung cong » dung cong, thong cong, hang cong
hanh hang » thanh hang, hang hang, hanh han
cua nhung » va nhung
vang toan » dang toan, quang toan, vang trang
hang cua » mang cua, hang ca, huong cua
van toan » van tuan, van tan, van thanh

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 sach) or (thien hach)) - hanh hang cua nhung cong ((vang toan) OR (van toan)) cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thieu sach) OR (thien hach)) - hanh hang cua nhung cong ((vang toan) OR (van toan)) cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thieu sach) or (thien hach)) - hanh hang cua nhung cong ((vang toan) OR (van toan)) cao".
• Adding a wildcard symbol may retrieve word variants: hoc ((thieu sach) or (thien hach)) - hanh hang cua nhung cong ((vang toan) OR (van toan)) cao*.