Perhaps you should try some spelling variations:
quang dai » quang dam, quang hai, quang ngai
van quang » van quan, tran quang, van tuan
cua quoc » cua thuoc
cua nuoc » cua nguoi, cua thuoc, nha nuoc
cam duc » cam xuc, cao duc, pham duc
duc van » duc va, duc tan, duc manh
tu sach » thu sach, su sach, te sach
lai hoi » dai hoi, lai hoa, lai roi
mai hoi » mai khoi, dai hoi, mai doi
hieu ve » hieu va, hieu van
ve cam » ve cham, ve cac, va cam
y nang » ky nang, ly nang, v nang

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach y nang ((mai hoi) or (lai hoi)). hieu ve cam duc van quang dai ((cua nuoc) OR (cua quoc))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang ((mai hoi) OR (lai hoi)). hieu ve cam duc van quang dai ((cua nuoc) OR (cua quoc)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang ((mai hoi) or (lai hoi)). hieu ve cam duc van quang dai ((cua nuoc) OR (cua quoc))".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang ((mai hoi) or (lai hoi)). hieu ve cam duc van quang dai ((cua nuoc) OR (cua quoc))*.