Perhaps you should try some spelling variations:
cua quoc » cua nuoc, cua thuoc
thanh va » thanh van, hanh va, thanh ha
mai khoi » mai khoa, tai khoa, cac khoi
duc van » duc va, duc tan, duc manh
cuc ban » cua ban, cac ban, cuu ban
tu sach » thu sach, su sach, te sach
hieu ve » hieu va, hieu van
mai hoi » dai hoi, lai hoi, mai doi
y lang » o lang, _ lang, tay lang
va cua » va chua, via cua, ca cua
ve cam » ve cham, ve cac, va cam

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 lang ((mai hoi) or (mai khoi)). hieu ve cam ((cuc ban) or (duc van)) thanh va cua quoc~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y lang ((mai hoi) OR (mai khoi)). hieu ve cam ((cuc ban) OR (duc van)) thanh va cua quoc.
• Adding a wildcard symbol may retrieve word variants: tu sach y lang ((mai hoi) or (mai khoi)). hieu ve cam ((cuc ban) or (duc van)) thanh va cua quoc*.