Perhaps you should try some spelling variations:
duy sang » duy van, duy can, duy anh
hanh lai » hanh lam, hanh tai, thanh lap
tu sach » thu sach, su sach, te sach
lai cua » dai cua, hai cua, lai chau
duoc va » nuoc va, duc va, duoc ma
va chat » van chat, va phat, cao chat
hieu va » lieu va, hieu qua
ky dang » ky nang, ky danh
cua tre » cua te, cuu tre, cua triet
doc va » hoc va, duc va, loc va
ma hoi » mai hoi, xa hoi, ma hoa

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 ((duy sang) or (ky dang)) ma hoi. hieu va chat ((doc va) OR (duoc va)) hanh lai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((duy sang) OR (ky dang)) ma hoi. hieu va chat ((doc va) OR (duoc va)) hanh lai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((duy sang) or (ky dang)) ma hoi. hieu va chat ((doc va) OR (duoc va)) hanh lai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ((duy sang) or (ky dang)) ma hoi. hieu va chat ((doc va) OR (duoc va)) hanh lai cua tre*.