Perhaps you should try some spelling variations:
vien cac » vien bach, vien dai, vien da
hanh tai » thanh tai, hang tai, han tai
van hanh » van thanh, ban hanh, van anh
su sach » so sach, vu sach
tai cua » thai cua, tai cuc, tri cua
xuc van » duc van, luc van, xuc ban
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach ty
nang ho » nang hoc, nang co, tang ho
ve cac » va cac
nang o » nang co, nang ro, nang x

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky ((nang o) or (nang ho)) hoi. hieu ((ve cac) OR (vien cac)) xuc van hanh tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((nang o) OR (nang ho)) hoi. hieu ((ve cac) OR (vien cac)) xuc van hanh tai cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky ((nang o) or (nang ho)) hoi. hieu ((ve cac) OR (vien cac)) xuc van hanh tai cua tre*".