Perhaps you should try some spelling variations:
thien van » thi van
doc sach » hoc sach, nuoc sach, dac sac
hanh lai » hanh lam, hanh tai, thanh lap
cham duc » pham duc, cham soc, pham duy
hieu van » hieu va, lieu va, hieu ve
toc sach » hoc sach, thuoc sach, nuoc sach
xang ma » tang ma, nang ma, sang ma
va hanh » van hanh, va thanh, va danh
lai cua » dai cua, hai cua, lai chau
cua tre » cua te, cuu tre, cua triet
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: ((doc sach) OR (toc sach)) ty xang ma hoi. ((hieu van) or (thien van)) cham duc va hanh lai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((doc sach) OR (toc sach)) ty xang ma hoi. ((hieu van) OR (thien van)) cham duc va hanh lai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((doc sach) OR (toc sach)) ty xang ma hoi. ((hieu van) or (thien van)) cham duc va hanh lai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((doc sach) OR (toc sach)) ty xang ma hoi. ((hieu van) or (thien van)) cham duc va hanh lai cua tre*.