Perhaps you should try some spelling variations:
chat duc » chat xuc, chat doc, chet duoc
hieu van » thien van, lieu va, hieu ve
van hanh » van thanh, ban hanh, van anh
sach ty » sach tu, sach thu, xach tay
hieu va » lieu va, hieu qua
duc van » duc va, duc tan, duc manh
hanh ca » hanh cac, hanh cat, hanh cua
cua tre » cua te, cuu tre, cua triet
ca cua » co cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: te ((sach y) or (sach ty)) nang x ho. ((hieu van) OR (hieu va)) chat duc van hanh ca cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach y) OR (sach ty)) nang x ho. ((hieu van) OR (hieu va)) chat duc van hanh ca cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach y) or (sach ty)) nang x ho. ((hieu van) OR (hieu va)) chat duc van hanh ca cua tre*".