Perhaps you should try some spelling variations:
hanh tai » thanh tai, hang tai, han tai
tham duc » pham duc, tham du, than duc
cua tre » cua te, cuu tre, cua triet
tai cua » thai cua, tai cuc, tri cua
va hanh » van hanh, va thanh, va danh
va tham » van tham, va cham, va thanh
hieu va » lieu va, hieu qua
bai ky » ban ky, sai ky, dai ky
ha hoi » hoa hoi, ha noi, va hoi
bac ky » cac ky, ban ky, sac ky

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

• Performing a fuzzy search may retrieve terms with similar spellings: te ((bai ky) OR (bac ky)) lang ((ha hoi) or (xa hoi)). hieu va tham duc va hanh tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((bai ky) OR (bac ky)) lang ((ha hoi) OR (xa hoi)). hieu va tham duc va hanh tai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((bai ky) OR (bac ky)) lang ((ha hoi) or (xa hoi)). hieu va tham duc va hanh tai cua tre".
• Adding a wildcard symbol may retrieve word variants: te ((bai ky) OR (bac ky)) lang ((ha hoi) or (xa hoi)). hieu va tham duc va hanh tai cua tre*.