Perhaps you should try some spelling variations:
lang dai » lang hai, lang mai, lang chai
chieu ke » hieu ky, hieu ve, hieu kem
su sach » so sach, vu sach
dai hoi » dai hoc, dai hai, dai moi
hanh vu » hanh vi, hanh va, hanh tu
ke cau » ket cau
luc va » tuc va, loc va
vu va » vu van, tu va, su va
thiet » thieu

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach _ lang dai hoi. chieu ke cau ((luc va) OR (duc va)) hanh vu va thiet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach _ lang dai hoi. chieu ke cau ((luc va) OR (duc va)) hanh vu va thiet".
• Adding a wildcard symbol may retrieve word variants: su sach _ lang dai hoi. chieu ke cau ((luc va) OR (duc va)) hanh vu va thiet*.