Perhaps you should try some spelling variations:
thanh doi » thanh loi, thanh moi, thanh do
thanh di » thanh de, thanh do, thanh dinh
vu sach » vu bach, su sach, vu khach
sach ky » sac ky, sach y, sach ty
hieu le » hieu ve, hieu he, hieu ly
nang ma » tang ma, sang ma, nang cao
ma thu » va thu
na thu » nam thu, va thu, ba thu

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ky nang ma hoa. hieu le ((na thu) or (ma thu)) va ((thanh di) OR (thanh doi)) cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky nang ma hoa. hieu le ((na thu) OR (ma thu)) va ((thanh di) OR (thanh doi)) cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ky nang ma hoa. hieu le ((na thu) or (ma thu)) va ((thanh di) OR (thanh doi)) cua vat".
• Adding a wildcard symbol may retrieve word variants: vu sach ky nang ma hoa. hieu le ((na thu) or (ma thu)) va ((thanh di) OR (thanh doi)) cua vat*.