Perhaps you should try some spelling variations:
cuoc sach » cuoc cach, cuon sach, nuoc sach
cua viet » hoa viet, cua vat, cua dieu
mai khoi » mai khoa, tai khoa, cac khoi
va hanh » van hanh, va thanh, va danh
truc va » thuc va, thuc vat, trung va
hieu ve » hieu va, hieu van
mai hoi » dai hoi, lai hoi, mai doi
ca viet » va viet, co viet, hoa viet
ve cau » ke cau, va cau, ve cac

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

• Performing a fuzzy search may retrieve terms with similar spellings: cuoc sach _ sang ((mai hoi) or (mai khoi)). hieu ve cau truc va hanh vi ((cua viet) OR (ca viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: cuoc sach _ sang ((mai hoi) OR (mai khoi)). hieu ve cau truc va hanh vi ((cua viet) OR (ca viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "cuoc sach _ sang ((mai hoi) or (mai khoi)). hieu ve cau truc va hanh vi ((cua viet) OR (ca viet))".
• Adding a wildcard symbol may retrieve word variants: cuoc sach _ sang ((mai hoi) or (mai khoi)). hieu ve cau truc va hanh vi ((cua viet) OR (ca viet))*.