Perhaps you should try some spelling variations:
vien cac » vien bach, vien dai, vien da
hanh tri » thanh tri, hanh tai, hanh trinh
van hanh » van thanh, ban hanh, van anh
cua tre » cua te, cuu tre, cua triet
nang co » nang cao, nang doc, nang noi
xuc van » duc van, luc van, xuc ban
tu sac » tu sach, tu cac, tu san
sac ky » cac ky, sai ky
nang o » nang ho, nang ro, nang x
ve cac » va cac

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 ((nang o) or (nang co)) hoi. hieu ((ve cac) OR (vien cac)) xuc van hanh tri cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky ((nang o) OR (nang co)) hoi. hieu ((ve cac) OR (vien cac)) xuc van hanh tri cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sac ky ((nang o) or (nang co)) hoi. hieu ((ve cac) OR (vien cac)) xuc van hanh tri cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sac ky ((nang o) or (nang co)) hoi. hieu ((ve cac) OR (vien cac)) xuc van hanh tri cua tre*.