Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
van thanh » ban thanh, van tuan
cua quoc » cua nuoc, cua thuoc
thanh di » thanh doi, thanh de, thanh do
nang mai » nang ma, nang tai, lang mai
duc van » duc va, duc tan, duc manh
tu sach » thu sach, su sach, te sach
ly nang » ky nang, ly hang, ly vang
mai hoi » mai khoi, dai hoi, lai hoi
di cua » dai cua, doi cua, de cua
va cao » va cac, va dao, va bao
va co » vo co

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) or (thuoc sach)) ly nang mai hoi. hieu ((va cao) or (va co)) duc van thanh di cua quoc~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thuoc sach)) ly nang mai hoi. hieu ((va cao) OR (va co)) duc van thanh di cua quoc.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thuoc sach)) ly nang mai hoi. hieu ((va cao) or (va co)) duc van thanh di cua quoc*.