Perhaps you should try some spelling variations:
thieu sach » chieu sach, thien hach, hieu cach
chieu sang » chieu sach, chieu xanh, hieu lang
nhung cong » dung cong, thong cong, hang cong
hanh tang » hanh trang, anh tang, hanh mang
cua nhung » va nhung
manh toan » thanh toan, anh tuan, tinh toan
tang cua » mang cua, hang cua, tang luan
dan toan » van toan, dan than, xuan 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 sach) or (chieu sang)) - hanh tang cua nhung cong ((dan toan) OR (manh toan)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thieu sach) OR (chieu sang)) - hanh tang cua nhung cong ((dan toan) OR (manh toan)) cau*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thieu sach) or (chieu sang)) - hanh tang cua nhung cong ((dan toan) OR (manh toan)) cau*".