Perhaps you should try some spelling variations:
dieu kien » dieu khien, dien bien
kien chao » vien cao, dien cho, khien cho
van hanh » van thanh, ban hanh, van anh
cac khoi » cac thoi, cac khoan, cach thoi
vai cua » dai cua, hai cua, lai cua
va hanh » va thanh, va danh, ban hanh
cua tre » cua te, cuu tre, cua triet
tu sac » tu sach, tu cac, tu san
me va » te va, ke va, le va
ky va » ly va, ke va, my va

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sac ((ky va) or (me va)) cac khoi. dieu kien chao xu ((va hanh) OR (van hanh)) vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ((ky va) OR (me va)) cac khoi. dieu kien chao xu ((va hanh) OR (van hanh)) vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sac ((ky va) or (me va)) cac khoi. dieu kien chao xu ((va hanh) OR (van hanh)) vai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sac ((ky va) or (me va)) cac khoi. dieu kien chao xu ((va hanh) OR (van hanh)) vai cua tre*.