Perhaps you should try some spelling variations:
khanh tai » thanh tai, hanh tai, nhanh thai
van khanh » van thanh, van hanh, van anh
tu sach » thu sach, te sach, tu cach
duc van » duc va, duc tan, duc manh
cac duc » cac du, cao duc, cac dac
hieu ve » hieu va, hieu van
cuc tre » duc tre, cua tre, cuu tre
su sach » so sach, vu sach
ve cac » va cac, vien cac
co hai » co dai, co hoi, so hai
o hai » so hai, o lai, _ hai

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) OR (su sach)) ky nang ((o hai) or (co hai)). hieu ve cac duc van khanh tai cuc tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) ky nang ((o hai) OR (co hai)). hieu ve cac duc van khanh tai cuc tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (su sach)) ky nang ((o hai) or (co hai)). hieu ve cac duc van khanh tai cuc tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (su sach)) ky nang ((o hai) or (co hai)). hieu ve cac duc van khanh tai cuc tre*.